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February 9

Is displaying phase information on an audio spectrum analyzer useful?

Like this and this where phase information is displayed as different colors. 2001:448A:3070:E573:5D44:3301:1481:FE0F (talk) 14:56, 9 February 2025 (UTC)[reply]

There is audio phase modulation to consider; see OOPS (stereo) for example. --136.56.165.118 (talk) 15:59, 9 February 2025 (UTC)[reply]

Yep but it is not related to phase part of FFT algorithm, which is necessary for reconstruction of audio signals from spectrogram but I'm curious about displaying the phase part of FFT spectrum. 2001:448A:3070:E573:5D44:3301:1481:FE0F (talk) 18:31, 9 February 2025 (UTC)[reply]

That FFT article mentions its inverse (IDFT), presumably its inverse phase. —136.56.165.118 (talk) 19:01, 9 February 2025 (UTC)[reply]

That's true but what I meant is visualizing the phase information actually useful and not give you a photosensitive epilepsy? As the inverse FFT is only used on audio processing in terms of spectral processing not analysis. 2001:448A:3070:E573:5D44:3301:1481:FE0F (talk) 07:31, 10 February 2025 (UTC)[reply]

Let's say you mixed two or more audio signals and it doesn't sound right; you might want to analyze the phase relationships. Phase information also helps identify time-domain issues like misaligned crossovers or reflections that cannot be corrected with EQ alone. It can be useful for aligning loudspeakers or optimizing PA systems. See also: Sine waves, phase and interference. Also see also: Bode phase plot. --136.56.165.118 (talk) 08:48, 10 February 2025 (UTC)[reply]

The phase information obtained by DFT or FFT analysis of sound is essential information for modelling an audio band communication channel or for analyzing room acoustics. Without phase information one cannot distinguish between amplitude-frequency nonlinearity caused by a time-invariant transfer function or caused by time delayed reflection(s) that are a subject for audio time delay reflectometry. Important requirements for the recording hardware that collects data for these analyses later are adequate dynamic range shown by input amplification/attenuation and the effective number of bits analog-to-digital conversion, adequate sampling rate and adequate time sequence memory. There may be no more need for real-time display than a minimum display to show when recording is in progress. However the OP who may not be interested in objective analysis asks about usefulness of phase in a real-time spectrogram display. There is subjective "educational" value in a phase visualisation because our hearing responds with well known characteristic to sound amplitude but is almost "blind" to phase in isolation. Smoothness or roughness of phase variation with frequency serves a qualitative hint at the kind of distortion occurring; this might prove helpful when positioning a microphone in a hall. We cannot speculate on this desk about usefulness of spectrograms as entertainment in video games, nor advise about deliberate or accidental triggering of epileptic seizure (PSE). Philvoids (talk) 12:18, 10 February 2025 (UTC)[reply]

West Indies Policing

After fourteen seasons, it has just emerged that Selwyn Patterson, the Commissioner of Police on the fictional island of Ste Marie, in the series Death in Paradise, has a superior, a Chief Commissoner, who is based in Jamaica. I see that Jamaica has its own police force, as do British dependencies such as Royal Cayman Islands Police Service. So is there in reality a pan-British West Indies police administration, that can order the appointment or dismissal of local police personnel?- Rojomoke (talk) 22:05, 9 February 2025 (UTC)[reply]

The country Jamaica consists of a main island, also named "Jamaica", and several small islands and islets, such as Pigeon Island, Salt Island, Dolphin Island, Long Island, Great Goat Island, Little Goat Island, Lime Cay, Morant Cays, Pedro Cays, and Port Royal Cays. (Some of these are actually themselves an island group.) Of these, Lime Cay has a popular beach; the islet is said to be a regular hotspot for post-party-goers and often swarmed with boats, music and socialites during holiday season (Summer and Christmas) weekends. Perhaps Ste Marie is a similar island in the Jamaica island group. ‑‑Lambiam 11:22, 10 February 2025 (UTC)[reply]

Thanks, good try, but Saint Marie is identified as a British Overseas Territory near Guadeloupe and Martinique, nowhere near Jamaica. Rojomoke (talk) 19:15, 10 February 2025 (UTC)[reply]

So the Brits managed to insinuate themselves into the French Antilles! ‑‑Lambiam 07:06, 11 February 2025 (UTC)[reply]

Irrelevant to my question, but British and French possessions are intermingled across the region. Dominica (former British territory and current Commonwealth member) lies between Guadeloupe and Martinique. Saint Marie is depicted as being a former French possession that was transferred to the UK in the 1970s. Rojomoke (talk) 07:46, 11 February 2025 (UTC)[reply]

In this interview, the Commissioner of the Royal Anguilla Police Force (Anguilla being a British Overseas Territory in the Caribbean), says that he is suuported by the National Police Coordination Centre, a branch of the UK National Police Chiefs' Council and the Foreign and Commonwealth Office. So I imagine that the Jamaican police Commissioner having jurisdiction over a BOT is just a fictional plot device. BTW, unlike the TV series, Anguila's Police Commissioners have been recruited from British police forces, the current one is from the Police Service of Northern Ireland, his predecessor was from Sussex Police. Alansplodge (talk) 17:56, 12 February 2025 (UTC)[reply]