Dummy Head Sound Production Tips and Pitfall

Mick Sawaguchi UNAMAS Label C.E.O

1 Background of dummy head reevaluation  

Recording with an old and new dummy head makes it easy to enjoy 3D space by targeting listening with headphones. I think that it will be a good tool for activation of mobile audio or smart phone recently and young people's headphones listening tendency, so I would like to introduce the dummy head recording from the production side. 

The idea of ​​a dummy head is to mimic the face of a person and record a small microphone into the ear part, can you faithfully reproduce the sound we hear on a daily basis? It started with the appearance of the prototype "Mr. Oscar" of the dummy head developed at Bell Research Institute in 1933. 

Especially in Europe, dummy head research is still continuing, and academic fields such as hearing research, acoustic field measurement, acoustic analysis, etc. Its characteristics are as described below.

● Popularization of mobile audio and popularization of digital music 　
players called DAP, adapted to the needs of listening to music easily anywhere Earphone listeners have increased, software optimized for headphones is also increasing its presence. it is not necessary to prepare separate MIX for achieving both speaker playback and headphone playback with the same sound source, so it is possible to provide a target with a balance that is optimal for listeners limited only to headphones .

● Dummy heads that can be used for recording and production have been introduced due to recent improvements in dummy head main body structure and improved sound quality of small internal microphones. Dummy heads of the 1980s had limited models of small microphones that can be used for built-in microphones, and its sound quality was not a preferable sound quality from the viewpoint of engineers.
Recently, the sound quality improvement of the miniature microphone is remarkable, and it is at a level that can be used sufficiently.

● Easily experience the 360 ​​degree surround sound field, since the spreading feeling of the sound field is localized outside the head, even when listening for a long time it is less tired than the sense of oppression due to the regular head position of the normal 2 CH stereo sound.

●The sound quality improvement of headphones and earphones has also
　advanced in recent years and the market of playback equipment called 　　　　
　high-quality DAP such as portable audio amplifier called Potaan and USB
　DAC connection etc. was formed and high quality playback became
　possible.

2 Utilize the features of dummy head  

Compared to microphones commonly used in studio etc., what kind of features does the dummy head microphone have?

● Front Center/ behind Orientation is poor
As dummy head researchers have pointed out, the dummy head is directly in front and the rear orientation is not good.

●   It is excellent for the reproduction of +/- 45 degrees on the side 　

centered on the ear and +/- 120 degrees above and below the head over the head.

●   Ambience recording of natural sound and music can express superior 

3D feeling.

The features of the above two points can be applied to how to use dummy heads recording, Meanwhile, the dummy head is a natural sound recording in the field and the ambience of the music recording.When using it as a microphone, the spatial reproducibility of the dummy head is successfully used.

To faithfully reproduce the sound field of the site to be recorded or the concert venue, it is necessary to pay attention to noise and background noise as much. If the level of the sound source to be recorded is high, you can not raise the S / N ratio because it can be high, but in small organized music and natural sounds of soft sounds, you have to be careful about that point. Even in studio recording, the performer's scripting noise, the squeaking of the performer's chair, movement etc. are clearly reproduced, so it can be said that this is a two-sided nature with the characteristic of realistic reproduction.

3 Utilizing the natural reproduction of 360 degrees  

It is a way of using the superiority of reproducing the3 dimensional space possessed by the dummy head as it is, so there is nothing to pay particular attention to. The choice of where to install for the sound source is the most important.

●   How to use as an ambience microphone in classical recording.

               

●Instrumentation of studio recording OFF Mike, how to use as ambience.

                                   

                                  

● Field Recording General: 

　Field recording is the same for normal equipment, but wind 　

　countermeasures are the basic, so dedicated wind shield covering the 

　ears of the dummy heads or even if there is still a shortage, please take 

　countermeasures against strong wind and rain are important.

4 　Dummy Head Drama Play production  

Drama production with a dummy head can be used not only to reproduce the feature of naturalness as described above but also various ways of using the front, rear, left and right, top and bottom localization from close-up to far-distance.

● Use objective and subjectivity separately
Among the dialogues, since the monologue is an effective expression when the headphone listener's in-head position is set, a normal microphone is installed at the center position of the dummy head to mix with the dummy head sound, a miniature microphone is dummy head There is a usage such as installing it in the center of, and using it together. In the drama, in the drama etc. where the story progresses by comparison of the subjective scene of the hero with the objective scene, it is possible to effectively use such contrast of the outward / inner rank like a POV.


●Use vertical feeling and ON-OFF distance sense

Since the vertical feeling and the sense of distance can be reproduced
well, the situations such as the conversation of the two people on the
roof and the downstairs and the conversation under the waterfall and
the flow under the scene may also be reproduced by the scene in real
physical situations It will be realistic if you arrange the performance in
the form of up and down of the dummy head. Even in sound effect
creation, you can also create space with that arrangement.

● Clarification of front / rear localization 

  +/- 45 degrees from the center of the ears, as mentioned above, that  

  the reproducibility is good, as mentioned above, there are times when 

  you want to express the localization just in front of you or in the real 

  world with a drama or the like. In such a case, the listener will make a 

  judgment including the prediction by not finding the position from the 

  front or the rear from the beginning, but by making the preroll a little bit 

  and adding a sense of movement and ultimately making it the front or 

  backward localization So the recognition of stereotaxis is improved.

● What about sound effects? 

  If you create a dummy head drama at an outdoor location, sound effects  

  other than speech can be used naturally as a sound caught by a dummy 

  head without discomfort, but if you want to express a sound effect with 

  intention, you need a little ingenuity . Foley material etc. If you place 

  Foley material sound in the necessary localization of the dummy head 

  and record it in the studio, Foley for the dummy head is completed. As 

  mentioned earlier, materials with low levels such as rusting clothes and  

  it may pick up the background noise inside the studio in three  

  dimensions, 

  so you should record at the Foley studio with a low NC value or when the 

  S / N ratio is severe, It is also necessary to forcibly choose not to record 

  with a dummy head.  Plug-ins that applied HRTF conversion technology 

  that it sounds like listening on the dummy head has also appeared (many

  binaural coding etc.), but when it can not be convinced with .

  Realistic solution is that to play back the sound source once to the 

  studio with a speaker and to rerecord it with the dummy head with the  

  method of"Worldizing".

For example, if you want to create a sound design such as an object falling from overhead, a flame running around 360 degrees, FLY-OVER going through the head over the missile group, set up 4 to 5 surround speakers Or you can play each sound source from up and down speakers, perform surround panning and rerecord with the dummy head installed at the center. There is no way to deteriorate in terms of sound quality, but by physically converting it to the HRTF transfer function via the dummy head, we can express the satisfaction better than the plug-in at present.

5 Balance attention point between on dummy head production and speaker playback

The dummy head has merit in that it can easily provide virtual reality to the headphone listener. As for the point of note when recording, microphone picks up every sound of 360 degrees with omni-directionality, so we recommend you to select a studio with less air conditioning noise. (Please use it if it is effective depending on the scene.) The dummy head is recommended without having to bother with noise due to the effect of location style recording outdoors.

The point of caution about speaker playback is that when you mix with headphones, the BG level such as music and bass sound and the ambience level such as reverb tend to be lower than the speaker playback, so please also check the balance by playing the speakers when mixing these scenes .
The sound recorded by the dummy head will be sound whose 4-5 KHz is emphasized and the vicinity of 8 KHz is attenuated due to its structure. Although it is not a particular problem in headphone playback, consonants etc. of serifs are emphasized when considering playing back speakers, so it is also important to keep the peak component at the time of recording with peak limiter etc.

6 What is suitable for a dummy head Production ? 

The reproducibility of the dummy head microphone is excellent if it is within 60 degrees with the ear tab as the axis. For this reason, the scenes such as the sound of the ear and oblique behind are effective so the story of the mystery or thriller psycho-touch is recommended. Adventure and spectacular stories are also genres that can be enjoyed with plenty of sound effects.

7 Dummy Head Mixing Tips

As mentioned above, the dummy head is not good at reproducing the center of the front and just behind. For this reason, in order to effectively utilize the sound field, sounds and localization are also effective if narration by the ordinary microphone and monologue recording are used together. Since the height also comes out a little, you should try the relationship between the top and bottom of the dummy head, for example the first floor and second floor scenes. Tools such as pan pot for dummy head are not currently in practical use, so we have difficulty in producing sound effects using 360 degrees. (There is a mixing console for RSS and dummy head, but it is not practical anymore ...) Also, there are not many different sound effects libraries recorded by dummy heads, and music also has less software to meet these objectives, so please think about the content balancing these points etc.

Even in Japan, people who recorded natural sounds with dummy heads and made them into CDs, and in the USA, Cesky Label produces music of various genres recorded by dummy heads for DAP listeners. If you have the opportunity, please experience dummy head production that can easily reproduce 3D stereophonic sound.

Mick Sawaguchi　Bio:Fellow member AES and ips 

1971 Chiba Institute of Technology graduated from Electronics Engineering, the same year started to work in NHK as a drama mixer, he is in charge of winning works such as Arts Festival Grand Prize, Broadcast Culture Fund Award, IBC Non-Bull Doll Award, Vatican Prize Winner.

From 1985 He has been deep involved surround production. He has been respected as "Surround Syogun". Since 2001, AES and Southeast Asia focused on workshops, seminars and technical presentations, promoting Asian surround production. SurroundTerakoya opened for promotion from 2002. Since 2007 he has launched the high-quality music production label UNAMAS label and is doing high-quality music distribution. The 4 times award winning on Japan Pro Music Recording by Hi-Res music .From 2015, focusing on immersive surround sound.

  http://unamas-label-jp.net.