Alright, are you getting a single "Ding!" out of a bell as you reach PD? The only time I hear bells (besides from when the wife whacks me with the cast iron skillet after "testing" SH4 too much) is for the Crash Dive:
For dive sounds... using the P or the D key should get you the regular "Ah-ooh-ga Ah-ooh-ga Dive!" Crash dive will get you what reminds me of my primary school's recess and period bell, that rings for five seconds or so, while you hear all sorts of "Give me 15° dive planes negative ballast..." blah blah and a similar though different "ah-ooh-ga ah-ooh-ga" horn blasts, and the telegraph goes to Ahead Flank. I get the same sounds each time I dive, consistent with the method used to dive, no matter what else happens around me, to the boat or anything else in the game, no matter how high I've gone with TC. So let's have you do some "testing" Fifi and anyone else with this.
From the surface:
1. Press the <P> key for periscope depth, and notate the sound you get. Surface again
2. Press the <D> key for dive (don't do time compression with this press), notate the sound and go however deep you want. Blow ballast to come back up to the surface.
3. Now press the <Ctrl><D> for "crash dive", notate the sound. Does your boat level-off at its crash dive depth? blow tanks again and come back to the surface.
4. As with following the instructions on a shampoo bottle, repeat. Stop whenever you get bored.
You could also try calling for Periscope Depth, change your mind, and do the <D> key before you get to PD, then do a <Ctrl><D> for crash dive right after that, and as long as you are above PD, you should get the sounds for all of them, even though you are no longer on the surface... just the nature of the game... Let us know what you get.
btw, I saw Heart open for Rush back in 1976 I guess (I had to do wikipedia to find the date... sheesh - I are old). St Louis MO, Fox Theatre, and it was the ~best~ sounding concert I was ever at. Only Lynyrd Skynyrd and Who at the St Louis Arena was a better show, and that was 1972 after Quadrophenia and Skynyrd's first album. Good times, yeah, good times. We were centered on the mezzanine, middle of the quad speakers. wow. LOUD!!!...