What is the best app to make rap beats?
Greg is right about Garage band, it’s quite good.Rapchat - pick a beat, record a freestyle rap, and share it on the App Store is also quite good. There’s also an interesting app called Rhymer’s Block that helps with writing for rap. We reviewed it when it was launched and liked it appPicker - Details Reviews
How do cell phones measure heart rate? Is it through optical sensors?
Yes. The heartrate sensor applied in smartphones consist of a LED and a optical sensor.To measure the heartrate, the subject needs to press their skin onto the unit in a way which avoids ambient light to leak in.The LED is then emitting light onto the skin, while the sensor is searching for a rhythm of color-changes in the feedback he receives.The rhythm is determinating your pulse then.In advanced solutions such a sensor can also estimate your blood oxygen level, by using a LED with a large spectrum and measuring the spectrum of light the sensor receives (depending on the oxygen level in the blood, the light is absorbed in a different way)See also here: Christoph Marschall's answer to How do Samsung's heartbeat sensor and oxygen saturation sensor work?
How does the mobile app Heart Rate Monitor work?
The science behind is every time your heart beats, more blood is pumped into your face. This slight increase in blood volume causes more light to be absorbed, and hence less light is reflected from your face. Almost every app in the market uses phone’s camera to track these tiny changes in reflected light that are not visible to the human eye and calculate your heart beat.For more information, you may be interested in this research paper which shows that this method can be done directly on the lens.
Heart rate too high?
I went for a quick jog earlier and I looked at my Apple Watch and it said my heart rate was 150... and this was with minimal exercise. Does this sound right or does my watch need calibrating? I’m not very active so this could be why it is high? I’m 16 so I doubt it’s anything to do with heart disease. To lower this, would I have to do more exercise? ☆ Sent from iOS Dr. Know! 1.1.03
How can I determine which tempo fits to my song before I start recording?
Long before I'm ready to record anything formally, I have played a new song dozens of times, possible hundreds. I have made the creative decisions the define that song to me. So by the time I'm ready to record something, I know the tempo. I may not know it in terms of beats per minute — though I have a good idea — but I know it.If you don't have a sense of the numeric expression of your tempo, no problem at all. You're just trying to nail down that number, you can try something that lets you tap you tempo. There are dozens of apps for this, even web sites. Find something you like. Or, just record the song as you play it, then run that recording through a bpm analysis app, another thing that's out there in the dozens. That will report your average bpm.Once you have that, practice playing to a metronome until you're solid. Maintaining a consistent bpm is the absolute key to mixing live recording and programmed music (MIDI, loops, etc). And it keeps your recording at a high standard. When you record, put a click track in your DAW and play to that.On the other hand, if you're still not settled on a tempo, you music isn't ready for recording. Or at least not formal recording with the intent of production. A quickie recording is fine… maybe record the new song, listen while you're doing other things, get a sense of whether that's the right tempo. And keep practicing!