That train whistle sound on "Wreck of the Old 97" by Johnny Cash

Cafe Society
1

On “Live at San Quentin”, Cash and his band play the 1924 ballad “Wreck of the Old 97”, about the 1903 train crash.

During two of the instrumental passages, there is a sound like a train whistle.

I assume it was a vocal effect, like Jimmy Rodgers does at the beginning of “Waiting on a Train”? If so, anyone know how it was done?

Or was it done with a device (like that whistle thing that Michael Scott had on his desk in “The Office”)?

2

Here’s a vid of Boxcar Willie doing it at Wembley in 1980 and there’s a close-up and he’s clearly vocalising it (somehow)

about 55s in

3

That sounds like a kind of Throat Singing, and is incredible.