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Warning: site autoplays a loud (presumably 50Hz) buzz...

• bumpty 4y ago
  According to http://hummingbirdclock.info/static/js/hum.js http://hummingbirdclock.info/static/js/hum.js the base frequency is 200 Hz, but has a gain of 4, which seems to push it more into the higher harmonic range as the waveform is clipped: // hum.js // toggle html audio on/off // with cookie to maintain state // and use html5 audio synthesis // ios html5 audio must be triggered // call init_hum() after DOM loaded // 0. create audio context // 1. create oscillator, define // 2. connect oscillator to gain // 3. create gain // 4. connect gain to output // 5. start oscillator (on click) var audio; var audio_context; var control; var vco, vca; var hum_delta = 1; var hum_base = 200; var hum_min = 100; var hum_max = 400; /* init */ function init_hum() { audio = get_cookie("audio"); console.log("audio = " + audio); audio_context = get_audio_context(); console.log("audio_context = " + audio_context); control = get_control(); if (audio_context != "false") { if (audio != "off") { set_hum(); hum_on(); } } else { set_cookie("audio", "off"); } } function get_audio_context() { var which_audio_context = window.AudioContext || // default window.webkitAudioContext || // safari false; this_audio_context = new which_audio_context; return this_audio_context; } function get_control() { var this_control = document.getElementById("control"); this_control.addEventListener("click", hum_on_off); return this_control; } function set_hum() { vco = audio_context.createOscillator(); vco.type = 'sine'; vco.frequency.value = hum_base; vca = audio_context.createGain(); vca.gain.value = 4.0; vco.connect(vca); vca.connect(audio_context.destination); } /* on off */ function hum_on() { set_hum(); vco.start(0); control.innerHTML="&times;"; set_cookie("audio", "on"); audio = get_cookie("audio"); console.log("audio = " + audio); } function hum_off() { vco.stop(0); control.innerHTML="+"; set_cookie("audio", "off"); audio = get_cookie("audio"); console.log("audio = " + audio); cleanup(); } function hum_on_off() { if (audio == "off") hum_on(); else hum_off(); } function cleanup() { vco.disconnect(0); } /* cookies */ function set_cookie(cname, cvalue) { document.cookie = cname + "=" + cvalue; } function get_cookie(cname) { var name = cname + "="; var ca = document.cookie.split(';'); for(var i = 0; i <ca.length; i++) { var c = ca[i]; while (c.charAt(0)==' ') c = c.substring(1); if (c.indexOf(name) == 0) return c.substring(name.length,c.length); } return ""; } function check_cookie(cname) { if (getCookie(cname) != "") return true; else return false; } The audio spectrum analyzer on my phone (Spectroid) records it most strongly around 1000 Hz.
  • jeffbee 4y ago
    At 50Hz it would be inaudible on most computers. https://szynalski.com/tone#50,v1 https://szynalski.com/tone#50,v1
    • tiborsaas 4y ago
      True, but cheating a bit with a triangle wave would solve it thanks to the harmonics.
• pqdbr 4y ago
  @dang Maybe you could add a [Loud sound] tag on the title. I clicked on it without knowing and blasted a huge noise from external speakers at midnight. Wife and neighbors are not happy.
• quickthrower2 4y ago
  Didn't do it for me. To test my headphones and ears, I tested a 50hz waveform on Youtube and could hear it.
  • exadeci 4y ago
    Didn't work for me at first, but I moved on the website pages and it did.
• account42 4y ago
  Why do (some?) browsers still let JS autoplay audio but not plain <audio> elements?