Figures such as -3 dB and -10 dB appear throughout loudspeaker specifications, but they do not describe an absolute level on their own. A decibel value expresses a ratio, so the reference and the quantity being compared matter.
Start with the reference
When a frequency response is described relative to a nominal or maximum level, the minus figure tells us how far the measured response has fallen from that reference. It does not mean the loudspeaker has reached silence, and it should not be read without the graph, tolerance or measurement conditions that accompany it.
Why the two figures are not interchangeable
A -3 dB point and a -10 dB point describe different relationships to the reference level. They can both be useful, but they answer different questions. Comparing products fairly therefore requires the same convention, the same kind of measurement and enough context to understand what has been published.
A number without its reference is incomplete information.
Use the worked guide
Ivan Beaver’s full Danley article works through the underlying relationships and examples in detail. Use the source link below when interpreting specification sheets or comparing published frequency ranges.