Study into an Individual’s Ability to Localise Sound in an Ambisonic

Environment Christopher Osborne 27thApril 2012 B00149787@studentmail.uws.ac.uk University of the West of Scotland Paisley Campus Paisley PA1 2BE I certify that all material in this essay/assignment which is not my own is duly acknowledged. I have read and understand the section in the school handbook dealing with plagiarism. Word Count: 6208

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Contents 1. Abstract Page 3 2. Introduction Page 4 3. Procedure Page 6 3.1 Questionnaire Page 6 3.2 General Hearing Test Page 7 3.3 Localisation Test using a 5.0 System Page 10 3.4 Localisation Test using an Ambisonic System Page 13 4. Findings Page 17 4.1 Questionnaire Page 17 4.2 General Hearing Test Page 27 4.3 Localisation Tests Page 29 5. Discussion Page 35 5.1 Variables Affecting General Hearing Levels Page 35 5.2 Variables Affecting Localisation Ability Page 37 5.3 Localisation Ability (5.0 vs Ambisonic Surround Sound) Page 40 6. Conclusions Page 46 6.1 General Hearing Health Page 46 6.2 General Localisation Ability Page 47 6.3 Implementation Page 48 6.4 Final Thoughts Page 48 7. Bibliography Page 49 8. References Page 50

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1. Abstract

Audio encoded then decoded with an Ambisonic Encoder/Decoder and played through an Ambisonic Surround Sound System can be localised more accurately by humans than audio played through a standard 5.0 Surround Sound System.

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2. Introduction

3D Technology has been implemented in various areas of entertainment and consumer electronics in recent years. Everything from cinema to video gaming has had 3D technology implemented into aspects of their functionality. These implementations are major technological advances and force other manufacturers to further research and develop better performing applications of the technology, which is of course very positive, however a large section of the consumer market is being forgotten about in these rapid developments. Around 10% of individuals do not have binocular vision (6 million people in the UK alone), meaning they cannot fully utilize their two eyes equally, commonly known as Stereo Blindness. Stereo Blindness is one of the main reasons that many individuals cannot fully see 3D images.

“3D is appearing everywhere, and there’s loads of people complaining they can’t see it…For these six million people, it’s like taking the 3D glasses off, making everything all blurry. It can create really bad headaches and aches behind the eyes.”1

In 2012 there are already 33 3D films lined to be given a worldwide release, compared to the solitary 5 3D film releases of just 3 years ago.2 With this major increase in 3D material being released many more individuals are getting to experience an extremely engrossing film experience, however many are also missing out. It is the view of the researcher that audio technology could also be implemented to not only enhance the 3D experience but also help engross audiences who have to view non 3D versions of films due to medical conditions. Ambisonic recordings and/or audio encoded through an Ambisonic Encoder possess unique attributes compared to standard audio recordings. The recordings themselves contain accurate directional properties that can be reproduced when the audio is decoded and played on specific speaker setups.

1DharmeshPatel,ChairmanofTheEyecareTrust,TheTelegraph,13thJuly20102MovieInsider.com

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Figure 1 – B-Format Sound Field Diagram3 Figure 1 displays the axial information that can be found in an Ambisonic track. Unlike standard surround sound setups, height information (Z Axis) can be stored within the track and reproduced along with X and Y Axis information, creating a full 3D environment. Theoretically the sound field created by an Ambisonic setup should be more immersive than a standard surround sound System as all 3 dimensions are catered for. Directionality, distance and height are can all be precisely recorded and reproduced. It is the researchers opinion that these attributes would lead to a more engrossing film experience for both 3D and non-3D viewers. Before an argument for the film industry to adopt this technology can begin, it is essential to first provide evidence that individuals are actually able to perceive a difference in the system compared to surround sound systems that are already common place in most cinemas and many homes. The key to this would be identifying whether sounds can be more accurately localized through the Ambisonic setup compared to a surround sound setup. If localization accuracy by individuals was greater through an Ambisonic setup an argument could be made that the technology would perform better in a film environment than current technology and should be adopted by the industry. The experimental research carried out and detailed in this paper aims to help support this argument through scientific approach, analysis and findings.

3http://media.soundonsound.com/sos/jun04/images/livesoundfielddiag.l.jpg

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3. Procedure

The experimental procedure of the research was split into 4 distinct sections; 1. Questionnaire 2. General Hearing Test 3. Localization Test carried out on a 5.0 Surround Sound Setup 4. Localization Test carried out on an Ambisonic Surround Sound Setup 3.1 Questionnaire The Questionnaire task taken by the participants helped determine a general profile of their hearing health by asking them their age and questions relating to sound environments they are currently in contact with (i.e. loud machinery in a factory environment), whether they use ear protection when they are exposed to loud noise and if they have any pre-diagnosed hearing conditions. The questionnaire did not give scientific accurate results however it gave the researcher a brief outline of their auditory profile, meaning any anomalies in the other three tests could be more easily explained. Participants were asked to mark, on a scale of 1-5 how often they listened to audio through headphones, how often they were exposed to loud noise and what level they regularly listened to audio at. They also gave details of pre-diagnosed medical conditions, whether they used ear protection when needed and what genre of music they listened to most. The Questionnaire’s marking scheme was developed after researching what effect certain variables have on auditory health. For the questions that asked the participant to rank their answer between 1 and 5, the number marked was taken as the score. If they said “Yes” to using ear protection when necessary they were given a score of -2, if not they were given 2. If they said, “Yes” to having a pre-diagnosed hearing condition they were given a score of 2, if not -2. Finally they were given a score of ¼ of whatever age they had given. All the scores were then added together to make an overall score. The genre of music the participant marked down was just used as reference when it came to analysing their individual results throughout the entire testing process. Although this was not a totally scientific approach it certainly helped identify individuals who had one or two variables that could dramatically influence the other tasks in the research experimentation.

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3.2 General Hearing Test The General Hearing Test gave the researcher an idea of the limitations of each participants hearing ability, allowing him to understand why certain frequency ranges used as part of the Localisation Tests may be impossible for certain participants to perceive. The test was carried out using a pair of Sennheisser HD650 headphones (see Figure 2) and Apple’s digital audio workstation, “Logic Pro”.

Figure 2 – Sennheisser HD650 Headphones4 Although these headphones are of a very high standard as with all audio reproduction devices the frequency response of the device is not perfectly flat. In order to overcome this I made sure the master track, which audio would go through last before being sent to participants, had an EQ plug-in applied to it that counteracted the flaws in the headphones frequency response.

Figure 3 - Frequency Response of Sennheisser HD650 Headphones

4http://cdn.head‐fi.org/3/34/34bc7e20_HD650Seite.jpg

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Figure 4 – EQ Applied to Master Fader in General Hearing Test A session was setup in Apple’s Logic Pro, containing 20 individual tracks, 10 panned fully left and 10 panned fully right in order to fully test both ears of each participant. These tracks were mixed randomly so that no patterns between the testing of each ear occurred. Tests tracks panned to the left were coloured blue while tests tracks panned to the right were coloured red. An Oscillator Pug-in was placed on each track and set to generate a tone of desired frequency.

Figure 5 – Oscillator Generating a 1kHz Tone

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10 varying frequencies between 50Hz and 15kHz were played to each ear in no specific order. Each track was played to the participant; they were instructed to say “Yes” if they could perceive the sound, “No” if they could not. Each track was played to participants first at -96dB; the level was then gradually increased until the absolute level was found (lowest level that the participant could perceive the tone at).

Figure 6 – Increase In Test Tone Level

There were also times when no tone would be played and the participant would be asked if they could hear anything, this helped ensure that the participants were carrying out the task correctly and not just saying, “Yes” to everything. Carrying out this type of procedure ensures that the MUSHRA method (Multiple Stimuli with Hidden Reference and Anchor Methodology) was being adopted, helping to remove flawed test data from the results. The researcher marked down participant’s absolute level for each tone on a Participant Testing Pack.

Figure 7 – Participant Having General Hearing Test

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3.3 Localisation Test using a 5.0 System In order to output the audio for the Localisation Tests a Motu 2408mk3 Interface was used along with 9 Genelec 8050a Monitors. The Motu Interface was used in order to allow a large number of audio channels to be output from the computer. In total 9 audio outputs and Genelec monitors were used, 6 for the Ambisonic testing and an additional 3 were needed for 5.0 Surround testing.

Figure 8 – Genelec 8050a Monitors

Figure 9 – Motu 2408mk3 Interface Localisation Tests using a 5.0 Surround Sound System were carried out as one of the participant tasks during the experimental research. The system was laid out in the standard format, with participants’ positioned 1.5 metres away from the centre speaker, angled directly in front of them at 0º.

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Figure 10 – 5.0 Surround Sound Layout Diagram All speakers were positioned at a height of 1 metre. No Low Frequency Emitter (Subwoofer) was used throughout testing, hence 5.0, due to the wavelength of the low frequencies reproduced by the speaker to be too long for humans to accurately localize. Therefore it would have added no useful data to the research. 14 sound bursts were created in order to test the participant’s Localisation Ability from various angles using various frequency bands. These were then set into a random order so that no pattern or themes were obvious. The 3-second sound bursts were created by recording three bursts of an oscillator emitting white noise. An EQ plug-in was then used to filter the signal until only one specific frequency band could be perceived. By only letting the participants hear short bursts instead of longer sound samples it ensured they had no time to over analyse the sample. Participants were also instructed not to move their head throughout testing. If the examiner noticed any movement the testing procedure was restarted and the order of the specific sound bursts/angles tested was altered.

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Figure 11 – White Noise Generator with EQ Plug-in Exposing Specific Frequency Bands 14 tracks were setup within Logic Pro and set to Surround Mode. Each channel was positioned at the angle detailed in the Sound Localisation Test Answer Sheet. Each participant’s testing pack contained an empty polar graph for him or her to mark the number of the tone at the angle they perceived it at. The examiner would clearly state the sound burst that was be played (e.g. Sound Burst 1), play the sample and then give the participant a few moments to mark down their answers. Sound Bursts were NOT repeated except in exceptional circumstances, e.g. fire alarm going off.

Figure 12 - Surround Panner set and placed on each Channel

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With an SPL meter set at -48dB, Range 60, Weighting A and with at the slow response setting the level of the sound blasts used for both the 5.0 Surround Sound and Ambisonic Localisation tests was 3dB. Natural room noise detected using the same SPL meter and settings was -13dB. 3.4 Localisation Test using an Ambisonic System The testing equipment and procedure used for the Ambisonic Localisation tests was very similar to that of the tests carried out using the 5.0 Surround Sound System. The main differences were the speaker setup and the software used to produce the audio.

Figure 13 - Ambisonic Surround Sound Layout Diagram The participant was positioned in the same position as in the previous tests with the speakers still positioned at a height of 1 metre. As no speakers were placed at higher or lower heights, the test carried out will only deal with Ambisonic Planar Reproduction.

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Reaper, a digital audio workstation program, was used instead of Logic Pro for the Ambisonic setup due to Reaper allowing the user to import VST Plug-ins, which the B-Format encoder and decoder were. The audio sound bursts used previously were recorded into a stereo audio track then imported into Reaper. This ensured that the sound bursts used in both localisation tests were identical.

Figure 14 – Sound Blast Audio Track Imported Into Reaper

In order to make the stereo audio track into an Ambisonic signal an Ambisonic Encoder was needed, a decoder would also be needed to enable the signal to be reproduced by the speaker setup created. The same frequency range and angle pairings, used in the 5.0 Surround Sound tests, were implemented again to keep consistency between the two tests. The B-Format encoder turned the stereo signal into a signal that could be reproduced on the Ambisonic setup, this then allowed the user to pan the signal to a desired angle. To save time during testing 14 presets were created into to quickly change between the various panning settings/angles.

Figure 15 – B-Format Encoder With Preset Loader

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Figure 16 – B-Format Decoder

The decoder was set to the standard Hexagonal Reproduction setting with Near-Field Compensation switched off. The procedure from the previous testing was adopted for the Ambisonic Localisation Tests. Participants were given an identical marking sheet to mark down the numbers of the sound bursts played, guided by the examiner.

Figure 17 – Complete Speaker Setup

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Figure 18 – Participant Carry Out Localisation Tests

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4. Findings All results were analysed and used in the most scientific and methodical way possible. Many measures were taken to ensure results given are as accurate as possible.

4.1 Questionnaire Age The age of the 18 participants who took part in the research ranged from 19-62, with 29 being the average age tested. The most common age of participants was 21.

Figure 19 – Age Against Overall Hearing Score

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Figure 20 – Age Against Localisation Score Using 5.0 Setup

Figure 21 – Age Against Localisation Score Using Ambisonic Setup

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On a scale of 1 to 5 (1 being never and 5 being daily) how often do you listen to music through headphones/earphones? The average answer given to this question was 4 with the most popular answer being 5. All participants gave an answer of 2 or more, meaning they all use headphones/earphones at least occasionally.

Figure 22 - Headphone Usage Against Overall Hearing Score

Figure 23 – Headphone Usage Against Localisation Score Using 5.0 Setup

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Figure 24 – Headphone Usage Against Localisation Score Using Ambisonic Setup

On a scale of 1 to 5 (1 being never and 5 being more than once a week) how often are you exposed to excessive loud noise? (E.g. nightclub, factory noise, loud gig) The average and most popular answer given to this question was 3. 78% of participants said they experience excessive noise levels of some degree, however the number who actually take precautions when experiencing excessive loud noise is much lower. Do you take precautions in these situations (e.g. ear protectors/ear plugs)? (Yes or No) Only 28% of participants marked “Yes”, they do take precautions in these situations. 72% said “No” they did not.

Figure 25 - Loud Noise Exposition Against Percentage of Hearing Protection Users

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Figure 26 – Use of Hearing Protection Against Overall Hearing Score

Figure 27 – Use of Hearing Protection Against Localisation Score Using 5.0 Setup

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Figure 28 – Use of Hearing Protection Against Localisation Score Using Ambisonic Setup

On a scale of 1 to 5 (1 being low and 5 being loudest possible) what volume do you set your iPod/car radio/hi-if etc to the majority of the time? The most popular answer and also the average answer for this question was 3.

Figure 29 - Usual Audio Volume Against Overall Hearing Score

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Figure 30 - Usual Audio Volume Against Localisation Score Using 5.0 Setup

Figure 31 - Usual Audio Volume Against Localisation Score Using Ambisonic Setup

What genre of music would you say you listen to most? A wide range of answers was given, however Rock (in various forms) was the most common choice.

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Do you have any pre-diagnosed hearing conditions (Yes or No)? Of the 18 participants asked only 2 (11%) had a pre-diagnosed hearing condition. What is this condition? The conditions stated were as follows; “Tinnitus” “Hereditary hole in my hearing spectrum and difficulty with fast changing sound (people that really speak fast)”

Figure 32 - Pre-Diagnosed Conditions Against Overall Hearing Score

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Figure 33 - Pre-Diagnosed Conditions Against Localisation Score Using 5.0 Setup

Figure 34 - Pre-Diagnosed Conditions Against Localisation Score Using Ambisonic Setup

When analysis of all data was completed, the overall questionnaire scores participants received were correlated with the overall scores the participants obtained in the other tasks.

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Figure 35 - Overall Questionnaire Score Against Overall Hearing Score

Figure 36 - Overall Questionnaire Score Against Localisation Score Using 5.0 Setup

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Figure 37 - Overall Questionnaire Score Against Overall Hearing Score All participants were sent an individual “Hearing Profile” from the researcher, detailing their individual results in each task and also highlighting areas they could improve on (i.e. use hearing protection when exposed to excessive loud noise). The profiles also advised them to seek medical advice if there were any anomalies/potential problems encountered during testing. 4.2 General Hearing Tests General Hearing Test results were analysed by creating three separate scores for each participant. A Left Ear, Right Ear and Overall (Combined) Score were calculated by adding up all the absolute values found for each participant in each category. The Overall (Combined) Score was calculated by adding the Left and Right Scores together. A higher hearing score suggests a participant has a greater level of hearing ability. For example a score of 40 refers to -40dB, this is quieter than -10dB, therefore a participant with a score of 40 can perceive sound that is -30dB quieter than a participant with a score of 10.

LeftEar RightEar Overall(Combined)MaximumScore 793 795 1564MinimumScore 481 466 947AverageScore 676 699 1374

Figure 38 – General Hearing Test Results By Ear

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Figure 39 – General Hearing Test Results By Frequency

Figure 40 – Difference Between Left and Right Ear Hearing Scores

On average the right ear perceived sound 23dB quieter than the left ear however on when both ears were tested with a 2kHz tone on average the left ear perceived the sound 2dB quieter than the right ear.

50Hz 100Hz 300Hz 500Hz 800Hz 1000Hz 2000Hz 5000Hz 10,000Hz 15,000Hz

MaximumScore 59 73 78 86 84 89 94 83 80 80

MinimumScore 29 45 66 72 73 73 60 25 7 0

AverageScore 46 63 72 78 79 81 79 74 65 49

Difference Between Left and Right Ear

Hearing Scores

Maximum -2

Minimum 15

Average -23

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Figure 41 – Average Participant Hearing Curve 4.3 Localisation Tests In order to analyse both of the Localisation Tests various techniques were implemented, the first being to analyse the standard deviation of the angles plotted by each participant for each sound burst of both of the tests. Standard Deviation is defined as “a statistical measure of spread or variability”5, which is essential to this research, as it is vital that the differences in participant perception between the two tests are investigated. In order to accurately analyse results angles have to be transposed slightly, meaning they had to be written as values between -180º - 180º. For example 330º would become -30.

5http://easycalculation.com/statistics/learn‐standard‐deviation.php

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Figure 42 – Standard Deviation Data of Both Tests

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Figure 43 – Standard Deviation of 5.0 Setup Against Ambisonic Setup The approximate angular differences between the actual angles and the angles plotted by the participants were also analysed to try to determine if the systems were more efficient at reproducing audio from specific angles.

Figure 44 – Average Angular Inaccuracy Between 5.0 and Ambisonic Systems (in º)

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Figure 45 – Average Angular Inaccuracy of 5.0 Setup Against Ambisonic System (in º) Each participant received graphs in their individual Hearing Profiles which detailed the directionality of the sound bursts and what angles they plotted at for the corresponding sound bursts on both tests. Figure 46 and 47 details the average angles plotted against each sound burst for each test.

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Figure 46 – Average Plots For Both Systems Against Actual Angles Used

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Figure 47 – Average Plots For Both Systems Against Actual Angles Used (Polar Diagram

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5. Discussion Numerical Data from various calculations is only part of what this research aims to identify. It is essential to analyse these figures and make sense of them in a practical sense. 5.1 Variables Affecting General Hearing Levels Figure 38 details how general hearing level was affected by age. The trend line shows a decrease in overall hearing score as the age of participant increases. A result similar to this would be expected as natural hearing loss occurs predominately due to age. If we look at the average hearing scores of participants above and below 30 years of age this theory is supported even further.

Figure 48 – Difference in Overall Hearing Score Between Participants Under & Over the Age of 30

The difference shown equates to an average difference of 143, this would mean that on average participants under 30 years of age perceived each test tone at a level -7dB quieter than that of participants over the age of 30.

Figure 49 – Average Hearing Curves For Both Participants Under & Over the Age of 30

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From Figure 49 it is apparent that both sets of participants perform well when test tones are under 2kHz. When test tones increase over 2kHz the average scores start to decrease rather severely. The frequency of which participants wear headphones looks to have a dramatic effect on overall hearing score. The trend line of Figure 22 seems to suggest that overall hearing level is increased as the frequency of headphone usage also increases. It is the researchers opinion however that this trend is only apparent due to a few anomalies. Only 3 participants marked down a headphone wearing frequency of under 3, out of these 2 of the participants were the lowest scoring in the General Hearing Test, causing the trend line to increase with frequency. It is the researchers view that no correlation between headphone wearing frequency and general hearing level has been found from this particular research.

From Figure 26 there does not seem to be any correlation between overall hearing score and the use of hearing protection. Although no correlation has been found on this occasion I think it is still essential that the use of hearing protection be promoted much more. Figure 25 highlights that just over a quarter (28%) of participants actually use ear protection when needed. If individuals want to be able to enjoy any type of high quality audio system later in life it is essential that the proper precautions be taken while their hearing spectrum is still complete. The same could be said about the effects of playing music at severe volumes. Although Figure 29 does not seem to show any negative consequences of always playing music at excessive levels, it has been proven by previous studies;

“Regularly listening to personal music players at high-volume settings when young, often has no immediate effect on hearing but is likely to result in hearing loss later in life.”6

Figure 32 shows that participants who did not suffer from any pre-diagnosed auditory conditions performed better than those who did throughout the general hearing tests.

Figure 50 - Difference in Overall Hearing Score Between Participants With & Without Pre-

Diagnosed Auditory Conditions The difference between the two average hearing scores is 250; this means that on average a participant with good auditory health perceived each test tone at a level -12.5dB quieter than that of a participant who suffered from a pre-diagnosed hearing condition. 6ScientificCommitteeonEmergingandNewlyIdentifiedHealthRisks,2008

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Figure 51 - Average Hearing Curves For Both Participants With & Without a Pre-Diagnosed

Condition

The difference in hearing curve between participants with and without pre-diagnosed conditions is immediately noticeable from Figure 51. Both sets of participants perform steadily until around 1kHz, when participants who suffer with condition’s scores then start to dramatically decrease. The devastating effects certain conditions can have on the ear’s ability to perceive the entire frequency spectrum humanly possible is very evident. When the relationship between overall questionnaire score and overall hearing score is studied (Figure 35) it shows that as questionnaire score rises hearing score decreases, this helps demonstrate that the questionnaire results are effective in giving participants and the researcher a rough estimation of their hearing profile. If they listen to loud levels of sound frequently without taking precautions they will receive a high overall score that is likely to be linked to a poor hearing score. 5.2 Variables Affecting Localisation Ability Age seems to be a factor in an individual’s Localisation Ability. Figures 20 and 31 both identify a trend between the two variables. As age increases so does inaccuracy. Figure 52 – Comparison of Localisation Inaccuracy Between 5.0 & Ambisonic Setups (inº)

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The table above highlights that on average the “over 30” inaccuracy score was greater than the corresponding score of the “under 30’s”. There is an average accuracy difference of 5º between participants under and over the age of 30 when the 5.0 systems is used. This difference reduces to 3º when the Ambisonic system is used. Figure 53 – Inaccuracy Curve of Participants Both Under & Over Age of 30 Using 5.0 Setup

(in º)

Figure 54 – Inaccuracy Curve of Participants Both Under & Over Age of 30 Using Ambisonic Setup (in º)

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The two graphs previous highlight the greatest inaccuracy difference between the two age ranges at the second and eighth sound burst tests through both systems. These sound bursts were played from angles of 210º and 0º respectively. The second test tone had a frequency range of 1.5-3kHz and the eighth had a frequency range of 12-16kHz. The greater inaccuracy score for the eighth sound burst could be explained by its high frequency range, which will be harder for older participants to perceive. The poor accuracy of the second test tone however would seem to be due to its angular positioning as the frequency range should be perceived well by the older participants (Figure 49). The frequency that participant’s use headphones and the volume which they regularly listen to music at does not seem to have any visible effect on localisation ability, however this is mainly due to the out of proportion results given by participants for the questions in the questionnaire that dealt with these issues. The reason for this will be discussed further in the next section (Critique). No relationship is visible between Localisation Ability and the use of hearing protection from Figure 27 & 28. This is due the fact that Localisation Accuracy was calculated by averaging all the angles the participants marked down - it does not take into account the sound bursts that participants could not perceive and hence failed to mark down a possible answer. If the number of “failed attempts” is analysed the following is found: All participants who use ear protection when necessary recorded only 6 “failed attempts” in total. However, when the total number of “failed attempts” by participants who do not use ear protection when necessary is counted the number rises to 14, over double that of the other group. Therefore the benefits of using ear protection are again highlighted. Figure 33 & 34 highlight how suffering from auditory conditions can affect an individual’s localisation ability. The overall accuracy of participants’ markings decreases if the participants have a pre-diagnosed hearing condition, however the difference is less when Ambisonic Test is compared to that of the 5.0 Test. Analysing overall questionnaire scores against localisation accuracy (Figure 36 & 37) participants with a higher questionnaire score (poorer auditory care taken/health) actually had greater accuracy in both tests when plotting angles they thought sounds were being reproduced from. However other factors can be taken into account that may put this “upset” into perspective. The majority of participants who use hearing protection are older and as described previously, older participants did not perform as well in the localisation tests as younger participants.

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5.3 Localisation Ability (5.0 vs. Ambisonic Surround Sound) By studying the difference between experimental data obtained from both Localisation Tests it becomes clear that the Ambisonic System produces more accurate results. When the difference in accuracy scores between the two age ranges is analysed (Figure 52) we see the difference in accuracy reduces from 5º to 3º. Figure 55 - Comparison of Participants Over 30 Years Old Performance With Both Systems

Figure 56 - Participants Over 30 Inaccuracy Comparison Curve (in º)

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By analysing Figure 55 & 56 one can see that 71% of sound bursts were, on average, marked more accurately by participants when they were played through the Ambisonic setup. The 29% of sound blasts that were plotted more accurately through the 5.0 System were of a high frequency range. It is the researcher’s opinion that the inaccuracy is likely to be due to the poor perception participants above the age of 30 seem have at high frequencies (Figure 49), rather than the Ambisonic setup having shortcomings at certain angles. Suffering from a pre-diagnosed hearing condition, as discussed above, seems to affect how accurately an individual can localise sound. The gap in accuracy between individuals with and without a pre-diagnosed hearing condition however seems to be less when an Ambisonic setup is used instead of a 5.0 setup.

Figure 57 – Comparison of Participants With Hearing Conditions Performance With Both Systems

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Figure 58 – Participants With Pre-Diagnosed Hearing Conditions Inaccuracy Comparison

Curve (in º)

Figure 57 & 58 shows how the two systems compared over the entire process of testing. As with the over 30’s group, 71% of sound bursts were plotted more accurately when the participants heard them being reproduced through the Ambisonic setup. Again the researcher feels that the poor perception of high frequencies common with participants who suffer from pre-diagnosed hearing conditions (Figure 51) contributed greatly to the 29% of sound blasts which were marked more accurately when played through a 5.0 system.

Figure 59 – Overall Comparison of Participant Performance Through Both Systems (5.0 &

Ambisonic) (in º)

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Figure 60 – Overall Comparison Curve of Both Systems (5.0 & Ambisonic) (in º)

Figure 61 – Difference in Accuracy Between Both Systems (5.0 & Ambisonic) (In º)

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Comparing the overall accuracy of both systems, it is evident that 79% of the sound burst tests were marked down more accurately when played through the Ambisonic System (11 out of the 14). 21% were marked more accurately when played through the 5.1 System (3 out of the 14). As discussed previously, the sound bursts that were marked down more accurately by the participants when played through the 5.0 systems were of a higher frequency band (7.9kHz-12kHz & 16kHz-20kHz). It would seem that on average higher frequency sound bursts are harder to accurately localise than lower frequency sound bursts - this could be due to variables discussed earlier (age, suffering from a pre-diagnosed condition etc). Figure 61 highlights the difference in accuracy between the two systems. Plots above 0 are sound bursts that were marked, on average, more accurately through the Ambisonic System. Plots below 0 were marked more accurately through the 5.0 setup. The most inaccurate results above 0 (Sound Bursts 4 & 7) were reproduced from angles between 135º and 225º. This seems to be the angular proportion of the testing environment that the majority of participants had difficulty localising correctly through both systems, more so through the 5.0 system. A common occurrence throughout the testing procedure was participant confusion when localising sounds positioned at 0º and 180º (Sound Bursts 7 & 8). Figure 62 – Sound Blast 7 & 8 Data (5.0 Setup) Figure 63 – Sound Blast 7 & 8 Data

(Ambisonic Setup)

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When audio is played from rear angles (135º - 225º) the Intraoral Phase Difference between the left and right ears is harder for the brain to calculate, causing localisation from these angles to be very uncertain, hence causing an increase in the chance of inaccuracy.

At 180 degrees, localization is almost completely uncertain. Regardless of the type of sound source, the overall tendencies of localization versus phase difference are similar, except for a sound source of impulsive nature.7

7PhaseDifferenceandSoundImageLocalization,TakeshiK.Matsudaira,TakeshiFukami,1973

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6. Conclusions Once experimental results are analysed and discussed it is important to put them into context. There are areas of the findings of this research that could be used to help better understand auditory health and listening habits in our current society and also the various advantages different surround sound systems may bring to various situations. Some sections of the research may need to be investigated further before they can fully be understood. The implementation of this research should also be clearly stated. 6.1 General Hearing Health The average hearing curve obtained from the testing carried out (Figure 41) seems to show what would be expected when compared to other results of similar tests, however there are certain concerns to be raised. The poorer perception possessed by older participants, over 30 in the case of this research, can be easily seen from data like Figure 49. The researcher noticed from the answers given in the questionnaire that older participants tend not to have used/currently use headphones as often as younger participants. They also tend to mark a lower score (1-5) when asked what volume they regularly listen to audio at. If older participants are showing significant signs of hearing deterioration at an age as young as 30, then younger participants, who from the data provided tend to use headphones more regularly and listen to audio at higher levels, will surely suffer hearing deterioration, maybe to a more severe scale and at a younger age. A great deal more attention has to be drawn towards auditory health and targeted at individuals of a young age. If individuals are encouraged to look after their hearing at a young age they may manage to adopt a regime (i.e. using ear protection when necessary) that will help slow down the rate hearing deterioration. Schemes should be structured and marketed similar to that of dental hygiene and sexual health initiatives. Although the effects of hearing deterioration might not seem as dramatic as the effects of poor dental hygiene or sexual health, the scale of hearing deterioration that will affect the young people of today is unknown. The consumption of audio through headphones and attendances at excessively loud festivals are at an all time high, this could lead to an unprecedented level of hearing problems in the future. The researcher noticed whilst carrying out General Hearing Test’s that the majority of participants had stronger hearing in their right ear, what is the reason for this? In the future the researcher would like to find out what hand the participants use most (i.e. left handed) and see if there is any correlation between preferred hand and most sensitive ear.

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6.2 General Localisation Ability When analysing the effects age has on Localisation Accuracy the researcher noticed that the difference in accuracy between younger participants and older participants was smaller when an Ambisonic System was used. The same trend was seen when sufferers and non-sufferers of pre-diagnosed hearing conditions were compared. The catalyst for this research was that many people were not able to experience 3D video technology due to various conditions. The researcher felt that 3D Surround Sound (Ambisonics) could be used to improve the 3D experience of film enthusiasts, especially those who may not be able to experience 3D films. Although no definite conclusions can be made it would seem from the results obtained that not only do Ambisonic Systems provide overall more accurate localisation but they can also provide an experience for individuals with poorer hearing which is not as far removed from what individuals with a good hearing level would be experiencing. Although the findings of this research are extremely encouraging there is still a great deal of experimentation and research that would have to be carried out in order to come up with the solid conclusion that Ambisonic Systems immerse individuals more than 5.0 Systems. The experimental procedure used in this research should be carried out using a full 3D Ambisonic System (extra speakers used to help aid in height reproduction). Testing could be carried out with a significantly larger number of speakers as there is no limit to the number of speakers that can be used in an Ambisonic setup. By carrying out numerous tests increasing the number of speakers used an optimum number of speakers could be found which helps aid localisation while still being practical (i.e. using 200 speakers is not practical in most environments). Thorough testing should be carried out on participants with a wide range of pre-diagnosed conditions. It is the researchers opinion that any audio system that is implemented into mainstream technology should be accessible and beneficial to as many people as possible. One of the reasons that some people get put off viewing 3D films is that someone they are with may not be able to watch it; hence the entire group abandons the technology. Testing should also be carried out using an actual film soundtrack instead of sound bursts. Although it would be harder to calculate Localisation Accuracy in a test like this, it would be much easier to get personal feedback from participants

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6.3 Implementation It is the researchers opinion that Ambisonic Systems should one day replace Dolby Surround Systems in most cinemas, however it would be extremely difficult for the technology to overtake Dolby, as it has had a major stronghold on the movie industry since the release of “Batman Returns” in 1992. The IMAX experience, although popular, is not dominant over the whole cinema industry, Ambisonic Systems could be implemented in a similar way to this. One or two cinema halls out of a multiplex could be fitted with the technology. Due to the versatility of Ambisonic technology, companies, such as Sky, could help launch the system in the home. Movie and television programmes soundtracks could be broadcast in UHJ Format meaning individuals who did not have the correct setup could still receive the signal through a standard stereo setup. If users of the service have a speaker setup the set-top box could implement a UHJ to B-Format convertor so that they could experience a full Ambisonic soundtrack. Unlike a standard 5.1 setup, users would not have to have the setup laid out in a specific manner, due to the nature of Ambisonic Systems as long as there are at least four speakers (Basic Planar Reproduction) in a rough symmetrical spatial reproduction can take place. The most likely way that the technology could become more common would be if more Blu-Ray releases adopted the technology as one of the additional soundtracks. Many major Blu-Ray releases come with numerous soundtracks (Stereo, 5.1, Directors Commentary, Various Languages etc). If Ambisonic versions of soundtracks were added to some major Blu-Ray releases it would dramatically increase the awareness of the technology. 6.4 Final Thoughts Equal-Opportunity schemes should not just be implemented in working and academic environments. The Entertainment Industry has a duty to deliver services to as many people as possible, regardless of their impairments. It is the researchers view that technology, that can bring enjoyment to a greater number of individuals than any other similar technology readily available, should be developed accordingly and made available to as many individuals as possible.

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7. Bibliography Auvinen, A. et al. (2008) Scientific Committee on Emerging and Newly Identified Health Risks.

Cheng, B. et al. (2008) A Spatial Approach To Ambisonic Audio Compression.

Everest, F. (2006) Critical Listening Skills For Audio Professionals. Boston: Thomson Course Technology

Katz, B. (2002) Mastering Audio: The Art and The Science. Oxford: Focal Press.

Ludman, H. (2007) ABC of Ear, Nose, and Throat. 5th ed. Oxford: Blackwell.

Matsudaira, T. and Fukami, T. (1973) Phase Difference and Sound Image Localization.

Rosenberg, M. (1982) Sound and Hearing. London: Edward Arnold.

Smith, S. (2003) Digital Signal Processing: A Practical Guide For Engineers and Scientists. London: Burlington Mass.

Tomlinson, H. (2008) Surround Sound: Up and Running. 2nd ed. Oxford: Focal Press.

Wyatt, H. (2005) Audio Post Production For Television and Film: An Introduction to Technology. 3rd ed. Oxford: Focal Press.

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8. References

Beaumont, C. (2010) Six million Britons can’t see 3D TV - Telegraph. [online] Available at: http://www.telegraph.co.uk/technology/news/7887422/Six-million-Britons-cant-see-3D-TV.html [Accessed: 7th April 2012].

CDN.Head-Fi.org (2012) Sennheisser HD650 Headphones. [image online] Available at: http://cdn.head-fi.org/0/07/265x265px-LS-07429eaa_B00018MSNI.01._SX250_SCLZZZZZZZ_V199155185_.jpeg [Accessed: 7th April 2012].

Easycalculation.com (2012) Learn Standard Deviation. [online] Available at: http://easycalculation.com/statistics/learn-standard-deviation.php [Accessed: 9th April 2012].

Movieinsider.com (2012) Movie Insider - Taking You Beyond The Studio Gates. [online] Available at: http://movieinsider.com [Accessed: 7th April 2012].

Sound On Sound (n.d.) B-Format Field Diagram. [image online] Available at: http://www.surround-library.com/images/white-papers/wp-b-format.jpeg [Accessed: 2nd February 2012].