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EE2F2: Music Technology - Revision. Two exam questions Music Recording Technology Mixing & multi-track recording Effects MIDI & Sequencers Virtual Studio Technology Sampling & Synthesis Sounds & Timbre Subtractive & Additive Synthesis Sampling & Digital Synthesis Physical Modelling.
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EE2F2: Music Technology - Revision • Two exam questions • Music Recording Technology • Mixing & multi-track recording • Effects • MIDI & Sequencers • Virtual Studio Technology • Sampling & Synthesis • Sounds & Timbre • Subtractive & Additive Synthesis • Sampling & Digital Synthesis • Physical Modelling
Mock Exam Paper Music Recording Technology. (a) Give two examples of dynamic effects and describe their effect on the sound. Limiting: Heavily attenuates loud portions of sound, limits the dynamic range to a preset range of amplitudes Compression: Partially attenuates loud sounds (not as much as a limiter). Compresses the dynamic range Overdrive: Soft-clipping effect, introduces extra harmonic content Distortion: Hard-clipping effect, typical rock guitar sound
A single comb filter creates a decaying echo effect: In Delay In Out + Time + Out Attenuation Time Several comb filters in parallel simulate multiple pairs of reflecting surfaces. The resulting impulse response is, therefore, similar to that of a real reverberant chamber. (b) Explain how comb filters can be used to create a reverberation effect.
(c) In the context of reverberation effects, outline the relative merits of comb filters and convolution techniques. Comb Filters: Computationally simple Easy to change parameters No need for acoustic measurements Convolution: Highly realistic Real buildings can be simulated
(d) What does the acronym ‘MIDI’ stand for? Musical Instrument Digital Interface (e) How can you tell the difference between a status byte and a data byte? Status Byte: Most significant bit is always 1 Data Byte: Most significant bit is always 0
(f) Explain the function of the following MIDI messages and list the information contained in each one: • Note On • Note Off • (iii) Control Change Transmitted at the instant a key is pressed to indicate the start of a note. Contains: MIDI channel, note number, velocity Transmitted at the instant a key is released to indicate the end of a note. Contains: MIDI channel, note number, release velocity Used to control parameters such as volume, panning, sustain pedal etc. Contains: MIDI channel, controller number, new controller value
(g) State two advantages of using virtual instruments and effects. Cost: Much cheaper than real instruments Size: They are virtual so they don’t take up any physical space Flexibility: Can be upgraded with software patches as easily as any other program Ease of Use: Large high resolution computer monitor with GUI controls rather than tiny LCD display Digital Output: Can be mixed with other virtual instruments using a virtual mixer and effects
Sampling & Synthesis (a) What advantages do modern digital samplers exhibit compared with analogue tape-based samplers like the Mellotron? High, digital audio fidelity No moving parts – more reliable Smaller and cheaper Random access memory means looping is possible
(b) Explain how the length of a sample can be extended using looping. After the attack portion, many samples don’t evolve that much. To save memory, this section of the sound can be repeated creating a potentially infinitely long sample. (c) What steps should be taken to ensure the looped sound is undistorted? Around the looping point, the sample must be continuous in terms of amplitude and of phase. Discontinuities in either will result in audible clicks.
(d) How can the pitch of a sample be altered? If the sample is played back at a faster rate, the pitch is higher; at a lower rate, the pitch is lower. Playback rate should be increased by a factor of 21/12 per semitone. (e) Explain how multi-sampled instruments work and why they are used. If the pitch of a sample is changed too much, it starts to sound wrong (‘squeaky’ if too high, ‘hollow’ if too low). Multi-sampling takes samples at more than one pitch spread across the keyboard. When a key is pressed, the sample closest in pitch is selected and scaled if necessary.
(f) Describe how sample & synthesis techniques can improve a sampled sound. A sampled sound always comes out the same regardless of key velocity, modulation etc. Also, only real sounds can be sampled. Sample & synthesis allows: Changing the amplitude and timbre of the sample in response to performance input. Creating entirely new sounds based on real samples.
(g) Compare the relative merits of analogue subtractive synthesisers, analogue additive synthesisers and digital FM synthesisers. Subtractive Synthesisers Relatively easy to program. Synthetic quality. Some timbres are impossible to synthesise Additive Synthesisers Difficult to program without computer assistance. Any combination of harmonics is possible. Limited number of oscillators leads to synthetic quality. Digital FM Synthesisers Very difficult to program. Highly realistic sounds possible with relatively few parameters.
Final Points • Keep your answers short – there are no marks for waffle • Look at all the material we covered: • Course notes • Lecture notes • Lab work