What is it?
As the name implies the device we built resembles the functionality provided by a metronome – so basically it’s a “click-machine”. But what is the difference between a standard metronome and the MMM? Well, imagine you, as a musician, hear a song on the radio and you think “heck, what a nice song, I might wanna try this at home”. With your standard metronome you’ll have to pay close attention and repeated trial and error to find the correct beat – and this is where the MMM kicks in. With our device you can simply snap your fingers to the beat and the MMM is going to hold it for you. This enables even more relaxed music making. Say you’re seated on the couch of your rehearsal room, your guitar on your knee and you need to adjust the beat of your metronome. No more putting aside your instrument and searching for the right setting, simply press the record button and either snap your fingers or maybe hit some strings to set the beat you want.
Furthermore the MMM comes with four LED-flashlights supporting beat recognition in dark and/or noisy areas – much like most rehearsal rooms are. The MMM even goes so far as to emphasize the first beat through a different color.
Finally the MMM also offers three different volume settings: Medium, ideal for your private training sessions; Loud, all you need at your rehearsal and mute, in case you don’t need any sound at all and simply want to have those flashlights as a guide for your band.
So, put in one sentence, the multimodal metronome is a combination of a metronome supported by flashlights in combination with a beat counter.
How does it work?
The basic components used to build the multimodal metronome are a speaker for sound output, a microphone for sound input, 4 LEDs for optical output, some switches and quite a few electrical components. Though this doesn’t sound like much the engineering journey we underwent to build it was rather bumpy.
First of all you need to know that the fathers of the almighty MMM are very pro-do-it-yourself, which means that we did not want to use any prewired or ready to use hard- and software, but to build this thing from scratch. Therefore we spent quite some time setting up and soldering down a microphone amplifier derived from here. The amplifier was then connected to a worn out headset microphone.
This amplification unit is needed to boost the incoming signal to a level recognizable by the Arduino Uno board – the core of the MMM. The amplification circuit we used was quite sophisticated, incorporating two potentiometers for fine adjustments of gain and amplification levels.
Next up was the speaker – a simple internal PC speaker. After some tests the team realized that the speaker, too, would need some form of amplification to support the high volume level required by the rehearsal room use case. The speaker therefore got its own, admittedly simpler, amplification circuit and a transistor enabling output triggered by the Arduino. The volume control also plugs into this speaker circuit controlling the aforementioned three sound levels.
Finally there is the LED-array – four clear light emitting diodes, a white one indicating the first beat and three orange ones for the rest of the beat. The smart reader might recognize the implication of this four-led-flash-beat-thing: it inevitably makes the MMM a rock-metronome!
All these parts are gathered at the heart of our device: the Arduino Uno, which is equipped with a sophisticated state machine, caring for smooth user experience.
The great pitfall
On our engineering journey we encountered one big pitfall that cost us at least one complete workday: a Sharp distance sensor. The background behind this thing is the pervading urge of the MMMs makers to design a whole new metronome experience. What we tried to facilitate was touchless control of the device by enabling gesture based beat recording.
Now what happened is that the aforementioned distance sensor caused so much interference that the microphone amplification unit couldn’t do it’s job anymore, but was biased by a disturbing signal rooted within the Sharp. Finding the source of the interference turned out to be really difficult, since we never worked on such a project before and had minimal electrical engineering background.
Values and potentials
The multimodal metronome is a gadget designed to simplify a musicians life. It combines the functionality of a beat counter and a metronome and supports beat perception by optical impulses. Therefore it’s main values and potentials lie in the domain of user experience and ease of use. Though, in its current state, the MMM still requires touch input to trigger beat recording, it became clear that with a distance sensor better suited for the purpose this goal is a reachable one. Also the combination of a beat counter and a metronome removes a device from your gig bag. So put together, the MMM resembles a multimodal combination of essential musical tools and helps musicians focus on what they do: keep on rocking!
Having achieved the first milestone of a working prototype, the next steps in line involve software optimization, sophisticated, stylish casing and enhancement of the optical output. The basic design sketch also incorporated a led-segment-display showing the current beats per minute – a feature postponed due to time limitations, that can and will be included within the next steps.