The dependence of a jet‐tone orifice numbertf/(Δp/ρ)12on Reynolds number[ρt(Δp/ρ)12]/μis shown for thin sharp‐edged circular orifices whose thickness and diameter both vary from approximately18to38in, wheretis thickness of orifice plate;f, frequency; Δp, pressure difference across orifice; ρ density; and μ, viscosity of gas. Each jet‐tone, in general, is composed of harmonics (fundamental and over‐tones) as well as subharmonics (tones whose frequencies are less than the fundamental). The subharmonics are relatively unsteady in amplitude compared to the harmonics and may at times have a greater amplitude. The jet‐tones at low Reynolds numbers appear relatively free of noise background. In general, as Reynolds number is increased to high values the noise background at first engulfs the subharmonics, then the harmonics. The fundamental is the last to remain, finally disappearing the noise background.