In article ,
"Clifton T. Sharp Jr." wrote:

Lloyd Randall wrote:
It sounds like an impedance mismatch. The input impedance for the M110
is 32 ohms, but GE doesn't seem to publish the output impedance for the
phone.

The last GE phone I bought came with its own headset; it was 150 ohms.
I suspect your phone might be as well. Natch, no headset worked with my
phone when the supplied headset broke; VERY low earpiece volume.

If a earphone were a resistive load, it would simply be too soft if the
source impedance were too high. In fact, earphones have mechanical
resonance at various frequencies. The higher the source impedance, the
louder these frequencies will sound, relative to other frequencies. The
output will wound harsh and distorted, and it will sound unclear because
some frequencies will be very soft.

With the GE phone, my M110 is harsh and unclear with some voices. I
think those are the voices that are strong in the frequencies where the
earphone resonates.

Telephone-line impedance is nominally 600 ohms. That would explain why
telephone headphones use to be at least 150 ohms. Earphones for
lightweight aviation headsets are nominally 600 ohms.

I think the walkman was responsible for the popularity of 32-ohm
earphones; with two penlight cells for a power supply, you couldn't get
loud music if the earphone impedance were much higher.

Is 32 ohms standard for cellphone headphones? If so, it may be because
walkman earphone elements were readily avialable. If cordless phones
don't use the same headphone impedance, could it be because
manufacturers don't want customers buying cheap cellphone headphones for
their cordless phones?

There must be inexpensive 150-ohm headsets or earphone elements
available. If only specs were easier to find!

--
Best Regards,
Lloyd