Friday, December 09, 2005

"How Loud Is My Voice Inside My Mouth and Throat"

In, “How Loud is My Voice Inside My Mouth and Throat?” one of the Journal of Singing’s articles for this year, Ingo R. Titze explains how the sound that is produced within the larynx is not the same sound that is heard by the listener. Now, he isn’t referring to tone color, or even resonance. What Mr. Tizte is talking about in this article is how the actual loudness of the sound is greatly diminished after leaving the throat.

Mr. Titze mentions two different terms which are usually related to sound intensity with loudness being the more common of the two. Loudness is actually what is referred to as a “psycho-acoustical measurement”. This means that loudness is a subjective term that has no specific definition or precise scale, but is subject to the internal interpretation of the listener. For example, at home my mother will often complain about that the television is too loud while my brother and I are watching it. We will not necessarily think that the volume of the television is too loud, but that is the way my mother perceives it. Even if I am you are borrowing someone’s headphones, for example, I doubt that you would leave it on the previous setting; we all have different opinions about what loud is. There is no specific level where loudness becomes present nor is there a specific level where loudness diminishes or becomes non-existent.

An example more pertinent and relevant to our lives as musicians is the deviation and differences in the same dynamic marking between different performers, or even the same performers playing the same piece at a previous or later time. We are taught from the beginning of our musical training that forte means to play loudly and piano means to play soft. Yet there is no one set level of volume for either of the dynamic markings, nor any dynamic markings for that matter. The fortes and pianos that one plays can depend upon the health of the performer, the particular instrument played upon, the size of the performing venue, and other various factors. The actual precision of the dynamics in a piece must then be measured in respects to the dynamics of all notes in sections in relation to each other. For example, the louder one’s normal forte, the less soft the performer’s piano. However, the player or singer’s fortissimo would have to be louder in order to be consistent with the forte and the other dynamic changes.

So in short, the loudness of sound is a subjective thing that is capricious and is set in accordance to many other volatile factors. Yet there is a way that scientists accurately measure the intensity of sound emission. They do this by measuring the sound pressure level, or SPL. While loudness is a subjective analysis, the SPL is actually a physical measure. In spite of this, the SPL is useful method of estimating what would be the generally perceived loudness.

This estimation is possible because of the standard reference pressure used to measure acoustic emission, 0.00002 Pascal. This particular level of sound pressure is so miniscule that it is just barely discernible even by the best ears in the most ideal surroundings. Our ears are able to manage sounds over a million times this reference pressure, however, so this logarithmic equation is used to calculate the SPL: 20 log10 P/P0 dB. The SPL is always measured in decibels. Inside of our vocal tract airway, the SPL can exceed 1000 Pascal.
Different areas of the air tract obviously have different pressures as well. The varying pressures consist of a great range of disperate levels. For example, the pressure in the lungs can range from 800 Pa to over 3000 Pa. The body is thus capable of producing sound well over the pain threshold.
So if our body is this great conduit of sound, why then does so much less pressure come across to our listeners? This is because the acoustic energy is emitted in a continuing circle outward from the head. This means that the sound is distributed across more surface area, which greatly minimizes on the SPL. Another cause is that much of our sound is reflected by our mouth, tongue and other internal structures, also diminishing the intensity of the sound.

In conclusion, the SPL is greatly diminished upon exiting the body because of the reflection of sound and the increase of area upon which the sound is spread. Within our own air paths the sound is significantly louder. Take in mind that if the sound were not so affected upon exiting the mouth, one would be able to hear a singer from a distance of twenty miles away. This is, of course, a hypothetical situation, but one that gives one a great appreciation for the natural, untampered power of the human voice.

Titze, Ingo R. "How Loud Is My Voice Inside My Mouth and Throat?" The Journal of Singing 19 (2005) : 177-178.

2 Comments:

Blogger Annie said...

When you presented-- I wasn't able to tell if everything you were saying was written out in script- so like Prof. said- make sure what you say is in the script, and waht's in the script is necessary.

Saturday, December 10, 2005 12:09:00 AM  
Blogger saxubatar said...

If you say "so in short" twice, it's not really in short.

Other then that, I wish I could sing...:'(

Saturday, December 10, 2005 11:26:00 PM  

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