For listeners with high-frequency hearing loss, there is a modified version of Songbirding which can be found under the name “Songbirding Under 5KHz”.
In this version, all frequencies about 5,000 Hertz have been halved – in music terms, it has been transposed down an octave. This means that musically speaking, sounds hit the same note, just at a lower register.
Many songbirds sing above 5 KHz. This number has been arbitrarily selected, but seems to represent the majority of high-frequency hearing losses.
There are some “side effects” to this adjustment: the human voice will sound slightly distorted to some, and birds whose songs hover around 5KHz mark will have sudden inversions that they would not normally have.
You can listen to these episodes on the web at 5khz.songbirding.com.