What is sampling, and how are recorded sounds manipulated and played as instruments?
Sampling and sample-based synthesis: capturing and triggering samples, the sampler and key mapping, looping, time-stretching and pitch-shifting, slicing and reordering, warping to tempo, and creative sample manipulation.
A focused answer to the Edexcel 9MT0 sampling content, covering capturing and triggering samples, the sampler and key mapping, looping, time-stretching, pitch-shifting, slicing and reordering, and creative manipulation.
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What this dot point is asking
Edexcel wants you to understand sampling: capturing a recorded sound and using it as musical material in a sampler, and the techniques for manipulating samples (looping, time-stretching, pitch-shifting, slicing, warping). You must explain how a sampler maps and transposes a sample across a keyboard and how samples are reshaped creatively. Sampling is central to Component 2 and recognising sampled material is examined in Component 3.
The answer
Capturing and triggering samples
Samples can be single hits (a drum sound), single notes (an instrument), loops (a drum break or phrase) or whole textures. Once captured, they become raw material to be shaped.
The sampler and key mapping
Looping, time-stretching and pitch-shifting
Looping turns a finite recording into a sustaining instrument; time-stretching and pitch-shifting decouple length from pitch, which a simple speed change cannot do (speeding a tape up raises both pitch and tempo together).
Slicing, reordering and warping
Examples in context
When a sampled string holds a long note, a loop is sustaining a short recording. When a vintage drum break locks to a modern track's tempo, time-stretching or warping has fitted it. When a chopped vocal is rearranged into a new melody, slicing and re-pitching are at work. Sampling and its manipulation tools turn any recorded sound into flexible musical material, which is central to the Component 2 composition.
Try this
Q1. What does time-stretching change, and what does it leave unchanged? [2 marks]
- Cue. It changes the length (duration); it leaves the pitch unchanged.
Q2. Why do realistic sampled instruments use multisamples? [2 marks]
- Cue. So each recording is transposed only a little, avoiding the unnatural sound of stretching one sample too far.
Q3. What does looping a sample achieve? [1 mark]
- Cue. It sustains the sound for as long as the note is held by repeating a section.
Exam-style practice questions
Practice questions written in the style of Pearson Edexcel exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Edexcel 9MT0/03 20214 marksExplain the difference between time-stretching and pitch-shifting a sample, and give one musical use of each.Show worked answer →
Time-stretching changes the duration (length) of a sample without changing its pitch, so a sample can be made longer or shorter while the notes stay the same. Pitch-shifting changes the pitch of a sample without changing its duration, so a sample can be raised or lowered in pitch while keeping the same length.
A musical use of time-stretching is fitting a sampled loop (such as a drum break or vocal phrase) to the tempo of a track so it plays in time without altering its pitch. A musical use of pitch-shifting is transposing a sample to a different key to fit the harmony, or pitching a vocal up or down for a creative effect, without speeding it up or slowing it down.
Markers reward time-stretch = change length not pitch, pitch-shift = change pitch not length, plus a valid use of each (tempo matching; transposition/effect).
Edexcel 9MT0/03 20234 marksDescribe how a sampler is used to play a single recorded note across a keyboard, and explain what looping a sample achieves.Show worked answer →
A sampler stores a recorded sound and maps it to the keys of a MIDI keyboard. A single recorded note can be assigned to a key (its root), and when other keys are played the sampler transposes the sample up or down in pitch (by changing its playback speed or using a pitch algorithm) so the one recording can be played as a pitched instrument across the keyboard. To sound natural across a wide range, several samples (multisamples) are usually mapped across zones so the transposition for each is small.
Looping a sample means repeating a section of it (typically a sustained portion) seamlessly, so that a short recording can be held for as long as the key is pressed. This achieves a sustained note from a finite sample, for example holding a sampled string or pad indefinitely without the recording running out.
Markers reward mapping a sample to a root key and transposing across the keyboard (ideally multisamples), and looping as repeating a section to sustain the sound for as long as the note is held.
Related dot points
- Subtractive synthesis: oscillators and waveforms, the voltage-controlled signal path (VCO, VCF, VCA), the filter and resonance, the ADSR envelope, the LFO and modulation, and how these combine to design a synth sound.
A focused answer to the Edexcel 9MT0 subtractive synthesis content, covering oscillators and waveforms, the VCO, VCF and VCA signal path, the filter and resonance, the ADSR envelope, the LFO and sound design.
- Other synthesis methods: additive synthesis (building from sine waves), FM synthesis (carrier and modulator), wavetable synthesis, the characteristic sounds of each, and how they contrast with subtractive synthesis.
A focused answer to the Edexcel 9MT0 synthesis content, covering additive synthesis from sine waves, FM synthesis with carrier and modulator, wavetable synthesis, their characteristic sounds, and the contrast with subtractive synthesis.
- MIDI and sequencing: MIDI as performance data not audio, note, velocity and controller messages, real-time and step input, quantisation and groove, programming drums and instruments with velocity and timing for a realistic result.
A focused answer to the Edexcel 9MT0 MIDI content, covering MIDI as performance data versus audio, note, velocity and controller messages, real-time and step input, quantisation and groove, and programming realistic parts.
- The digital revolution: the move from analogue to digital audio, the compact disc (1982), MIDI (1983), the digital sampler, hard-disk recording and the rise of the DAW, and software pitch correction such as Auto-Tune.
A focused answer to the Edexcel 9MT0 digital history, covering the move from analogue to digital, the compact disc (1982), MIDI (1983), the digital sampler, hard-disk recording, the DAW, and Auto-Tune.
- Capturing and editing audio: setting levels and recording cleanly, non-destructive editing, cutting, trimming and moving regions, comping the best take, crossfades to avoid clicks, fades, and removing noises and breaths.
A focused answer to the Edexcel 9MT0 capture and editing content, covering recording cleanly, non-destructive editing, cutting and moving regions, comping, crossfades, fades, and removing noises.
Sources & how we know this
- Pearson Edexcel A-Level Music Technology (9MT0) specification — Pearson Edexcel (2017)