I've been listening the masked track at night, but last night I tested the ultrasonic track and I have to raise the volume on my Galaxy S2 to almost full (3 or 4 steps from full volume) in order to hear it. I can always hear the ultrasonics through speakers when calibrated normally. I also tried another set headphones (plugs) and with those I only had to use half the volume or less. I also tested with playing the ultrasonic and putting the SleepPhone speaker right up to mic hole of my phone and got maybe -60 to -50dB at full volume with Frequensee. The other earplugs gave a lot more.
Just posted this as a warning and also to ask are your SleepPhones the same? Even with normal music, or the masked track, its clearly audible that there's not much HF. It should be ok, just feels a bit unsafe playing the US track at full volume every nigth... The masked track is fine, but I'm a bit worried that I sometimes have to turn the track volume so low to be able to sleep that the actual suggestions will be too low in volume (Shannon said they're 40-60 dB if I remember it rigth).
Just posted this as a warning and also to ask are your SleepPhones the same? Even with normal music, or the masked track, its clearly audible that there's not much HF. It should be ok, just feels a bit unsafe playing the US track at full volume every nigth... The masked track is fine, but I'm a bit worried that I sometimes have to turn the track volume so low to be able to sleep that the actual suggestions will be too low in volume (Shannon said they're 40-60 dB if I remember it rigth).
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