What was that you sang?

Much of birdwatching is in fact birdhearing. You hear the "butchers boy" whistle of a Bullfinch long before you locate the bird itself. In a wood, the Nuthatch announces its presence with a piping phrase, and it is only then that you seek to see it. A penetrating whistle from a watercourse draws your attention to a Kingfisher and with luck you may see it. And so on.
As this is Friday evening and I am in Old Scrote mode, I wish to complain to Whoever Makes the Rules In This Universe that I am losing the ability to hear the higher frequencies. So, for example, I can no longer hear Goldcrest, Treecreeper or Lesser Spotted Woodpecker. Even the pinging of Bearded Tits is getting harder for me to pick up.
There's no point in complaining of course. God clearly favours the young. If he didn't, my knees would still work properly.
But there could be a glimmer of hope, a technological breakthrough in fact. There is a machine called a Bat Detector that picks up the frequencies of batcalls that are inaudible even to the sharpest human ears, and you - or the people in the know - can identify the species from the pitch and other characterisics of what the Bat Recorder records. The Bat Detector can also be used to pick up the various calls of Crickets and Grasshoppers.
So, methinks, maybe I should buy a Bat Detector and thereby get a visual equivalent on the LSD of what I can no longer hear when a Goldcrest or a LSW warbles its "I'm home, dear!" message to the missus.
Bugger, I've just realised the flaw in my Cunning Plan: I might get a readout, but how will I know what species it represents? Have you noticed how often technology offers you a solution but then throws up problems to prevent you from benefiting from it?
All this because I bought a router a week ago, and I am STILL trying to get it to work.