“Textural density” in audio is the (partly successful) appropriation of a term in music which refers to the way that instruments/voices and their respective musical lines in a musical composition are used. Each musical line is a “layer” and the “density” of the composition refers to the overall character of the sound as determined by the number of layers employed in the composition. One or few layers results in a “thin” musical texture. Many layers, a “thick texture”.
I think one can then extrapolate and in audio, if one thinks of the naturally occurring harmonics in musical sounds as “layers” themselves, a reproduced musical sound which expresses an accurate (natural) number and combination of harmonics can be said to be “texturally dense”. One that is lacking in full harmonic expression can be said to be “thin” or “threadbare”.
I think one can then extrapolate and in audio, if one thinks of the naturally occurring harmonics in musical sounds as “layers” themselves, a reproduced musical sound which expresses an accurate (natural) number and combination of harmonics can be said to be “texturally dense”. One that is lacking in full harmonic expression can be said to be “thin” or “threadbare”.