(Lecture 8) Voice Timbre: Characteristics and Shaping

Defining Timbre:

• Timbre refers to the unique characteristics of a voice or instrument that are separate from its pitch (frequency) and loudness (amplitude).

• It can be conceptualized as the 'color' or 'personality' of a sound.

• While instruments have timbre, the focus here is specifically on the timbre of the human voice.

Timbre as Energy Distribution:

• Timbre is fundamentally about how energy is distributed across the spectrum of hearing frequencies.

• For speech and voice, meaningful information typically exists below $5 ext{ kHz}$ to $6 ext{ kHz}$, so analysis is often limited to this range.

• Energy bands within the spectrum can be boosted (enhanced) or damaged (cancelled/attenuated) spectrally, impacting the overall sound quality.

Factors Shaping Timbre (Changing Energy Distribution):

1. Vocal Fold Approximation:

   • Firmness/Looseness:

     • Firm Approximation: Vocal folds press together firmly, as in producing a loud sound.

     • Loose Approximation: Vocal folds come together lightly, as in a softer, breathier sound.

     • Super Breathy Voice: Vocal folds may come close but not touch, creating a 'big open phase' where a lot of breath passes through.

   • Depth of Approximation:

     • Thick Vocal Folds: Vocal folds approximate from their bottom edge to their top edge, producing a 'chesty,' 'speechy' voice often used in lower registers.

     • Thin Vocal Folds: Vocal folds approximate primarily at their upper edges, resulting in a 'lighter,' 'smaller' voice quality, referred to as 'head voice' or 'falsetto.'

     • Thicker vocal folds are perceived as louder and having more 'presence' or 'oomph,' while thinner vocal folds are perceived as quieter and gentler.

2. Shape of the Vocal Tract:

   • The vocal tract, extending from the outlet of the larynx to the back of the mouth, significantly influences timbre.

   • Vowel Sounds: The tongue position for different vowels drastically alters the vocal tract shape, impacting resonance:

     • /i/ (e-vowel): Tongue is high and front, opening the throat space widely (e.g., 'ee' in 'see'). This configuration tends to create an 'anti-formant region' where certain frequencies are cancelled.

     • /a/ (ah-vowel): Tongue is low and back, closing off the throat space (e.g., 'ah' in 'father'). This configuration leads to a convergence of energy in a different spectral area.

     • Spectral patterns differ even in whispers (no harmonics) vs. glottal fry (no periodicity, thus no harmonics) vs. voiced speech (with harmonics).

   • The Pharynx:

     • The pharynx (tube from skull to esophagus) plays the biggest role in timbre shaping, even more than the mouth, nose, or larynx itself.

     • It is the primary area, aside from vocal fold depth, for shaping timbre.

Three Ways to Shape the Pharynx (Timbre):

1. Top to Bottom - Vocal Tract Length (Larynx Position):

   • The larynx can move up and down by as much as $2$ to $3$ vertebrae.

   • Low Larynx Position:

     • Mechanism: Larynx is lowered (e.g., during swallowing, consciously pulling down via muscles).

     • Effect on Vocal Tract: Elongates the pharynx (vocal tube).

     • Effect on Sound: Enhances lower resonances, resulting in a perceived 'low,' 'dark,' or 'hollow' sound, even if pitch remains constant. This can stereotypically be associated with characters perceived as 'dumb' or 'slow.'

     • Impact on Piriforms: The piriform sinuses (spaces leading to the esophagus) widen, acting as 'anti-resonators' that cancel high-frequency energy (typically above $4 ext{ kHz}$ or $5 ext{ kHz}$ depending on individual anatomy), creating a spectral 'gap' or loss of high-frequency energy.

     • Example (Adverts, Cher): Often used for deep, resonant voices.

   • High Larynx Position:

     • Mechanism: Larynx is raised (e.g., consciously pulling up via muscles).

     • Effect on Vocal Tract: Shortens the pharynx.

     • Effect on Sound: Enhances higher resonances, resulting in a perceived 'higher,' 'brighter,' or 'childish' sound.

     • Impact on Piriforms: The piriforms close off, increasing energy in the $4 ext{ kHz}$ to $5 ext{ kHz}$ range.

     • Example (Child-like voices, cartoon characters): Patrick from SpongeBob is an example of high larynx with added LMN.

   • Mid (Neutral) Larynx Position:

     • Mechanism: Larynx is in a resting, unforced position.

     • Effect on Sound: Produces a timbre that is 'speech-friendly' and highly intelligible, as it enhances frequencies crucial for consonants and vowels.

     • Usage: Often preferred by speakers and singers (e.g., folk singers, musical theater) when clear message transmission is important.

2. Side to Side - Lateral to Medial Narrowing (LMN):

   • Mechanism: Involves the contraction of the pharyngeal constrictor muscles (the same muscles used for swallowing) to narrow the throat from side to side (lateral to medial).

   • Simultaneous Larynx Movement: It is impossible to narrow these muscles without simultaneously raising the larynx. Therefore, LMN automatically leads to a shorter and narrower vocal tract.

   • Effect on Sound: Adds 'brightness' or 'twang' to the sound. This is due to the narrowing of the piriforms, which prevents the cancellation of high-frequency energy, boosting energy typically above $4 ext{ kHz}$ or $5 ext{ kHz}$.

     • This high-frequency energy is sometimes called 'cricket energy' and contributes to the 'rock and roll snare' sound.

     • Historically, Richard Paget (1930) described 'American twang' with similar throat narrowing.

   • Misconception for Singers: Many singers mistakenly aim for an 'open throat,' but effective, brilliant singing often involves throat narrowing (LMN).

   • Visual Cues: A 'Nashville squint' or 'big squint' (squinting of the eyes, particularly in the upper vocal range) is an observed technique that can help singers achieve twang.

   • Nasality and LMN: LMN is not inherently nasal. It can be produced with or without nasality (by lowering or not lowering the velum). Perceptually, people sometimes confuse the 'bright' LMN sound for nasality because it 'feels' like it's in the nose.

   • Examples: Bluegrass singers, opera singers (for brilliant high notes), certain cartoon characters (e.g., Karen from Will and Grace with her 'fabulous' voice).

Lab Assignment for Students:

• Identify examples (speech or singing) for:

  • Low larynx position.

  • Mid (neutral) larynx position.

  • High larynx position.

  • Lateral to medial narrowing (LMN).

• Examples provided in class (which cannot be used for the assignment):

  • Darth Vader: Low larynx (