On Thu, 1 Jul 2004 19:43:02 +0000 (UTC), "Reg Edwards"
wrote:

I am writing a program involving an antenna plus two coupled tuned circuits
plus a matched simple receiver.

I would like to know, crudely, the audio power input level to 2000-ohm, iron
diaphragm headphones for a nice, comfortable, not too difficult listening
level. Such as when the phones are used on a crystal and cat's whisker
radio receiver.

Odd, I was just corresponding over this very matter recently.

Such headphones are more sensitive than modern 8-ohm varieties. I have a
pair of 2000-ohm headphones but unfortunately no means of measuring power or
voltage input.

Then we step into the area of conjecture.

Just the number of micro-watts please. At what low power input level does
speech or music just BEGIN to fade out to a person of normal hearing? Any
ideas? I could take the average of a few replies.

Hi Reg,

This will be have to be done through inference or Web research. As
far as inference goes, I will first state that magnetic speaker
efficiency is extremely poor, but I don't know if this extends to the
headphone implementation. Albeit, between 1 and 10% efficient.

The level of hearing for a child or teen fades out at 1db re
environmental impositions. Technically, in the absence of other
sounds:
1dB re 200µDynes per cM² at 1KHz

0dB = 200µDynes per cM² = 0.1 femtoWatt per cM²

a quiet whisper = 6 femtoWatts per cM²

conversation at 1M = 1 nanoWatt per cM²

Hearing at another frequency such as 400Hz (common sidetone for CW) is
10dB weaker (hearing peaks about 5dB in the 2-4KHz region) and worsens
as frequency lowers.

Hearing loss in the 50-59 Age group for men at 1KHz is about 10dB

Given "hearing" is subjective, a technical response is only as
accurate as the knowledge of these variables (age, sex, frequency,
efficiency).

73's
Richard Clark, KB7QHC