That's legendary guitar player Edward Van Halen at the beginning of the show asking, "Hello, hello, can you hear me?" The irony of his not being able to hear Frasier during their call is that Van Halen played immensely loud rock music. Also, Eddie would have known very well the dynamics of microphones and radio broadcasting technology.
At KACL, Frasier (Kelsey Grammer) gives a time check of 4:25, which indicates that he has a coveted "drive time" slot, probably 2-5 or 3-6.
This is the first time it is revealed that Niles (David Hyde Pierce) gets nosebleeds when he violates his ethics.
The Act One, Scene Four title card--"KIss Me, Kate"--is a nod to the 1948 Cole Porter Broadway musical of the same name.
The title is from the song "Call Me Irresponsible" composed by Jimmy Van Heusen, with lyrics by Sammy Cahn and was made popular by Frank Sinatra.