Following recent discussion on harp-l and SlideMeister of bass and baritone harmonicas, here are some mp3s to give an idea of the sound of each.
I have samples three different instruments here. Each example starts on the D nearly two octaves below Middle C (which I will call Baritone D), then proceeds to demonstrate some of the features of the instrument.
This is an all-blow instrument with single reeds. Its lowest note is Baritone D and it ranges up two octaves to the D just above Middle C. The notes are arranged in a chromatic scale, with one semitone per hole.
The audio example starts on Baritone D at the bottom of the instrument's range, then ranges up to the top D just above middle C.
This is the standard bass harmonica. It has two harmonica bodies, or decks. All notes are blow notes and each note has two reeds tuned an octave apart. The lower-octave reed is the intended note while the upper-octave reed reinforces the lower.
The lower deck of the No. 265 starts on E nearly 3 octaves below Middle C and ranges up two octaves through fifteen notes. The lower deck has only the natural notes, no sharps or flats. The upper deck has fourteen notes starting on F and ranging up to Eb. It includes all the sharps and flats as well as B natural.
The audio example for the No. 265 starts on Baritone D, then moves down to the low E, then up to the high E, then back to the starting point on Baritone D.
The instrument played here has the same range as the No. 265 bass. However, it has only the low octave reeds, so you can hear the sound of a single-reed harmonica in the low bass range.
This instrument also has both blow reeds and draw reeds in the same hole. The blow reeds give the natural notes while the draw reeds give sharps, flats, and a duplicate C. This was achieved by cannibalizing a Huang 123 bass and taking the low-pitched C#-scale reedplate from the upper deck and installing it upside-down on the lower deck opposite the low-pitched C reedplate, replacing the high-octave C reedplate. By installing it upside down, the C# blow reeds became draw reeds. With a blow low-C reedplate and a draw low-C# reedplate, I have a completely chromatic bass harmonica in a single body.
This example starts on Baritone D and goes down to low E. The lowest notes take more preparation to sound than on a standard bass, as you can hear. This is partly a matter of adujsting attack pressure and partly a matter of mouth resonance. At a few points I alternate the blow and draw reed in the same hole. Note how audible the change in wind direction becomes with these large reeds.