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Listen to and read a recording

Every recording shows two synchronized views: an oscillogram (waveform over time, above) and a spectrogram (frequency over time, color for loudness, below) — the spectrogram is usually the more useful one for telling calls apart, since a bat's call shape (its frequency sweep, its pulse spacing) is exactly what a spectrogram makes visible. Move your mouse over either and a small box next to the cursor shows the exact time/frequency under it.

Click anywhere on either graph to start playback from that point; a moving line tracks the current playback position.

Time Expansion vs. heterodyne playback

Bat calls are mostly above human hearing, so both playback modes make them audible in different ways:

  • TE (×10) — the default. Playback is slowed down tenfold, which also drops every frequency by the same factor into human hearing range. This preserves the call's whole shape, just stretched in time.
  • HET — heterodyne: mixes a tunable frequency band down to audible range in real time, at normal speed, the way a bat detector's built-in speaker works in the field. Set the kHz value by hand, or click ⟲ to reset it to the frequency Fledermap auto-tuned for this recording. HET only makes the chosen band audible — a call outside it won't be heard at all — so TE is the better choice for actually hearing everything in a recording, and HET for confirming a specific frequency.

Recording-detail page tools

Open a recording's own page (Details, from the map drawer) for a larger, locked-scale view with its own toolbar:

  • Default — click to play from that point, drag to pan across a long recording.
  • Ruler — drag to draw a measurement box, showing elapsed time (ms), the equivalent pulse-repetition rate (Hz), and frequency span (kHz) between two points. A plain click clears it.
  • Lock view — freezes horizontal scrolling to the current window, so repeated playback (e.g. replaying a short stretch several times to pick out one call's detail) always plays exactly the same range instead of auto-following into whatever's next.