Spectrogrammetry; plotting the energy versus frequency over time
The metallic jip call is probably the best indicator, but even this needs to be recorded and analysed on a sonogram to confirm the identity.
Partiels (1975) is a defining piece of Spectral music by Gérard Grisey whose opening is derived from an electronic sonogram analysis of the attack of a low E2 on a trombone.
The first satellite UV spectrogram of a planetary nebula (IC 2149 in Auriga) was obtained, revealing lines of aluminium and titanium - elements not previously observed in objects of that type.