The Tweek

[fragments of voices and jingles broadcast over shortwave]

[Cuban radio announcer]
Radio Cuba, Havana, Cuba

[American radio announcer]
At the tone, three hours, fifty-three minutes, Coordinated Universal Time

[interlocutor]
What is the difference--the distinction--between a swish and a whistler?

[engineer]
Well, a swish descends through the audio frequency spectrum with time, whereas a whistler is more coherent

[interlocutor]
In other words, the whistler is a rarified and specialized case of the swish

[engineer]
Well, we find some which start out like a swish and end up like a whistler, and we call these "swishlers"

[interlocutor]
They're audio frequencies, but they're not audible unless you have radio ears

[engineer]
That's correct. They're audio frequency radio waves

[interlocutor]
We've talked about whistlers a lot, now perhaps we should just devote no more than a minute or two to the tweek

[engineer]
The tweek is rather well understood. I demonstrate that these are indeed tweeks, but that the rate of decline in tone is so fast, that they're not recognizable as well-developed tweeks until you slow them down

[interlocutor]
A mature tweek is one that's many miles away

[engineer]
If it's a crash or a bonk, and if it's far enough away so that it's not that but not a tweek, it's one of these immature tweeks

The dawn chorus, on the other hand, is not at all well understood, and there is no theory to explain it

[warbling unidentifiable announcer]