Recruitment, HyperRecruitment, Decruitment…

Yes, I know… some of you may think I’m abusing terminology here. And I may be. But I have yet to find a consistent definition for these terms.

So everywhere in this Blog, I will take ownership of those terms to mean these specific things:

  1. Recruitment hearing is the usual result of overexposure to damaging levels of sound, or perhaps from illness or drugs, that causes an elevation in the threshold of hearing by varying amounts at each frequency, generally rising with increasing frequency. It produces the sensation of rapidly increasing loudness levels as the presentation rises gradually above the elevated threshold, becoming finally near normal at loudest presentation levels.
  2. HyperRecruitment is an excess of recruitment hearing, such that sounds regain their perceptual levels more rapidly than under recruitment hearing, as they rise above elevated threshold levels. This often continues until sounds reach uncomfortable levels when they shouldn’t be.
  3. Decruitment is a deficit in recruitment such that as presentation levels rise, the perceived levels rise more slowly than with recruitment hearing, and never reach the perceptual levels they ought to, even at very loud levels.

So there… be mad at me for bending your terms. I am a physicist and I needed names for these three categories of hearing. So I simply stole these terms from you. I use them like Humpty Dumpty would use them – “to mean whatever I choose them to mean”.

But at least now you know precisely what I mean.

There is another term bandied about in these pages that ought to be more carefully described – Apparent Perceptual Loudness, either with or without the application of hearing corrections. You see that term everywhere along the vertical axis of all my compression and recruitment graphs.

  • Apparent Perceptual Loudness – means the loudness level that would be perceived by normal hearing for the same presentation level. If a hearing correction produces a level of X dB in apparent perceptual loudness, that means that normal hearing would sense a level of presentation of X db.

By presenting my graphs in terms of “Apparent Perceptual Loudness [dB]” versus “Presentation Loudness [dB]”, I can avoid the unnecessary diversion into the topic of Sones versus Phons measure. The latter are the actual equational terms, but would bend graphs into unfamiliar shapes. I think it is easier to speak to people in terms that describe their experience, rather than some abstract mathematical space.

  • DM

[ Heh! When someone from the audiology community can’t understand equations, but wants to exert their authority, I usually receive the sharp rebuke that “You don’t even use the correct terminology!”.

If the irony eludes you, they completely miss my points, but their response allows them a sense of superiority.

I say, go read some of Richard Feynman, and realize that names have no meaning until we define them. Only the objects have innate meaning. And I just defined the names and their associated objects. So do the translation to your own language if you need to. I define my names most precisely by using the lingua franca of science – equations.]

[… this disjunction with language reminds me of a story my wife told me about when she had to take Statistics in college for her Psychology graduate degrees. They spoke in class about the “values” of a mathematical variable, and she took offense at their use of that term for such purpose… Heh! ]