question: why do adults voices change when they become elderly?
comment: You know how older people have wrinkly skin because bodies get looser as we age? This also affects the body parts we use to produce the sound of our voice.
passages: The facial bones begin to grow as well. Cavities in the sinuses, the nose, and the back of the throat grow bigger, thus creating more space within the head to allow the voice to resonate. Occasionally, voice change is accompanied by unsteadiness of vocalization in the early stages of untrained voices. Due to the significant drop in pitch to the vocal range, people may unintentionally speak in head voice or even strain their voices using pitches which were previously chest voice, the lowest part of the modal voice register.
  
  Section::::History.
   Most of the voice change begins around puberty. Adult pitch is reached 2–3 years later but the voice does not stabilize until the early years of adulthood. It usually happens months or years before the development of significant facial hair. Under the influence of androgens, the voice box, or larynx, grows in both sexes. This growth is far more prominent in boys than in girls and is more easily perceived. It causes the voice to drop and deepen. Along with the larynx, the vocal folds (vocal cords) grow significantly longer and thicker.
   Older adults (older than 65 years) with no or minimal hearing loss show benefit from phonemic restoration. In some conditions restoration effect can be stronger in older adults than in younger adults, even when the overall speech perception scores are lower in older adults. This observation is likely due to strong linguistic and vocabulary skills that are maintained in advanced age.
  
  Section::::Factors.:Gender.
  
  In children, there was no effect of gender on phonemic restoration. 
   The age effects were studied in children and older adults, to observe if children can benefit from phonemic restoration and if so, at what capacity, and if older adults maintain the restoration capacity in the face of age-related neurophysiological changes. 
   Historical changes in the average age of puberty have had profound effects on the composing of music for children's voices. The composer Joseph Haydn (1732–1809) was known for typically singing parts in high pitches throughout his 17th year.
  
  Unchanged voices were in high demand for church choirs, which historically excluded women. The British cathedral choir ideal remains based on boy sopranos (or trebles), with the alto part executed by adult countertenors. But in German-speaking countries the alto parts as well are sung by boys.
   Section::::Physiological process.
  
  In the modal register, the length, the tension, and the mass of the vocal folds are in a state of flux which causes the frequency of vibration of the vocal folds to vary. As pitch rises, the vocal folds increase in length and in tension, and their edges become thinner. If a speaker or singer holds any of the three factors constant and interferes with the progressive state of change, the laryngeal function of the voice becomes static and eventually breaks occur resulting in obvious changes in vocal quality.
   Section::::Development.:Adulthood.:Impact of hormones.
   Under the influence of androgens, the voice box, or larynx, grows in both sexes. This growth is far more prominent in boys, causing the male voice to drop and deepen, sometimes abruptly but rarely "overnight," about one octave, because the longer and thicker vocal folds have a lower fundamental frequency. Before puberty, the larynx of boys and girls is about equally small. Occasionally, voice change is accompanied by unsteadiness of vocalization in the early stages of untrained voices. Most of the voice change happens during stage 3-4 of male puberty around the time of peak growth. Adult pitch is attained at an average age of 15 years, although the voice may not fully settle until early twenties. It usually precedes the development of significant facial hair by several months to years.
   Section::::Development.:Old age.
   Vocal fold phonatory functions are known to change from birth to old age. The most significant changes occur in development between birth and puberty, and in old age. Hirano et al. previously described several structural changes associated with aging, in the vocal fold tissue. Some of those changes are: a shortening of the membranous vocal fold in males, a thickening of the vocal fold mucosa and cover in females, and a development of edema in the superficial lamina propria layer in both sexes. Hammond et al. observed that the HA content in the vocal fold lamina propria was significantly higher in males than in females. Although all those studies did show that there are clear structural and functional changes seen in the human VF which are associated with gender and age, none really fully elucidated the underlying cause of those changes. In fact, only a few recent studies started to look at the presence and role of hormone receptors in the VF. Newman et al. found that hormone receptors are indeed present in the VF, and show a statistical distribution difference with respect to age and gender. They have identified the presence of androgen, estrogen, and progesterone receptors in epithelial cells, granular cells and fibroblasts of VF, suggesting that some of the structural changes seen in the VF could be due to hormonal influences. In this specific study, androgen and progesterone receptors were found more commonly in males than in females. In others studies, it has been suggested that the estrogen/androgen ratio be partly responsible for the voice changes observed at menopause. As previously said, Hammond et al. showed than the HA content was higher in male than in female VF. Bentley et al. demonstrated that sex skin swelling seen in monkey was due to an increase in HA content, which was in fact mediated by estrogen receptors in dermal fibroblasts. An increase in collagen biosynthesis mediated by the estrogen receptors of dermal fibroblasts was also observed. A connection between hormone levels, and ECM distribution in VF depending on age and gender could be made. More particularly a connection between higher hormone levels and higher HA content in males could exist in the human vocal fold tissue. Although a relationship between hormone levels and ECM biosynthesis in vocal fold can be established, the details of this relationship, and the mechanisms of the influence has not been elucidated yet.
   Age-graded variation
  
  In linguistics, age-graded variation is differences in speech habits within a community that are associated with age. Age-grading occurs when individuals change their linguistic behavior throughout their lifetimes, but the community as a whole does not change.
  
  Section::::Definition.
   Section::::Development.:Adulthood.:Maturation.
  
  Vocal fold structure in adults is quite different from that in newborns. Exactly how the VF mature from an immature monolayer in newborns to a mature three layer tissue in adults is still unknown, however a few studies have investigated the subjects and brought some answers.
   Although middle-aged adults have conservative speech as mentioned above, older adults tend to have less formal speech. Older women who have passed the years of childbearing shed some of the conservatism in their speech. Similarly, older men who are past the age of retirement and no longer in the workforce also have less formal speech because of reduced social pressure to conform.
  
  Section::::Studies/examples.
  
  Section::::Studies/examples.:"Zed" vs. "zee".
   Section::::Development.:Adulthood.:Impact of phonation.
   All the same, accents are not fixed even in adulthood. An acoustic analysis by Jonathan Harrington of Elizabeth II's Royal Christmas Messages revealed that the speech patterns of even so conservative a figure as a monarch can continue to change over her lifetime.
  
  Section::::Non-native accents.
   I played child parts till I was 14, 15, then my voice changed. So I decided to learn a trade and went to a vocational high school in New York. I studied to be a furrier, but I never worked at it. As soon as I graduated high school, I went to a stock company in Pittsburgh, a Jewish theater, and I played there for 38 weeks, and that's where I actually learned my trade a little bit as an adult.
   During speech, the respiratory cycle is modified to accommodate both linguistic and biological needs. Exhalation, usually about 60 percent of the respiratory cycle at rest, is increased to about 90 percent of the respiratory cycle. Because metabolic needs are relatively stable, the total volume of air moved in most cases of speech remains about the same as quiet tidal breathing. Increases in speech intensity of 18 dB (a loud conversation) has relatively little impact on the volume of air moved. Because their respiratory systems are not as developed as adults, children tend to use a larger proportion of their vital capacity compared to adults, with more deep inhales.
   Voice change
  
  A voice change or voice mutation, sometimes referred to as a voice break, commonly refers to the deepening of the voice of people as they reach puberty. Before puberty, both sexes have roughly similar vocal pitch, but during puberty the male voice typically deepens an octave, while the female voice usually deepens only by a few tones.
   The human voice is in a constant state of change and development just as the whole body is in a state of constant change. A human voice will alter as a person gets older moving from immaturity to maturity to a peak period of prime singing and then ultimately into a declining period. The vocal range and timbre of children's voices does not have the variety that adults' voices have. Both boys and girls prior to puberty have an equivalent vocal range and timbre. The reason for this is that both groups have a similar larynx size and weight and a similar vocal cord structure and color. With the onset of puberty, both men and women's voices alter as the vocal ligaments become more defined and the laryngeal cartilages harden. The laryngeal structure of both voices change but more so in men. The height of the male larynx becomes much greater than in women. The size and development of adult lungs also changes what the voice is physically capable of doing. From the onset of puberty, the human voice is in an in-between phase where it is not quite a child's voice nor an adult one yet. This is not to suggest that the voice stops changing after puberty. Different singers will reach adult development earlier or later than others, and as stated above there are continual changes throughout adulthood as well.
   Infants vocal tracts are smaller, and initially also shaped differently from adults’ vocal tracts. The infant’s tongue fills the entire mouth, thus reducing the range of movement. As the facial skeleton grows, the range for movement increases, which probably contributes to the increased variety of sounds infants start to produce. Development of muscles and sensory receptors also gives infants more control over sound production.
   Hinckley's annual speeches at BYU were the subject of a study by the National Center for Voice and Speech at the University of Utah to analyze how the human voice changes with age. Thirty-six speeches by Hinckley were analyzed, ranging from 1958, when he was 47-48, to 2007, the year prior to his death. The study showed how his voice started dropping in pitch in his 50s and continued until he was 70, after which he began to develop a higher, thinner "old person" voice. By his 80s, his voice became increasingly wavery and the rate of his speech began to slow and by his 90s, he would slur words. Hinckley was a good subject for the study as the annual addresses were meticulously recorded and transcribed, in addition he did not smoke, drink, sing, or engage in other activities that would put unnatural strain on his voice.
   The infant lamina propria is composed of only one layer, as compared to three in the adult, and there is no vocal ligament. The vocal ligament begins to be present in children at about four years of age. Two layers appear in the lamina propria between the ages of six and twelve, and the mature lamina propria, with the superficial, intermediate and deep layers, is only present by the conclusion of adolescence. As vocal fold vibration is a foundation for vocal formants, this presence or absence of tissue layers influences a difference in the number of formants between the adult and pediatric populations. In females, the voice is three tones lower than the child’s and has five to twelve formants, as opposed to the pediatric voice with three to six.
   The vibratory portion of the vocal fold in the anterior glottis is connected to the thyroid cartilage anteriorly by the macula flava and anterior commissure tendon, or Broyles' ligament. Posteriorly, this vibratory portion is connected to the vocal process of the arytenoid cartilage by the posterior macula flava. The macula flava in newborn vocal folds is important for the growth and development of the vocal ligament and layered structure of the vocal folds. In the adult, the macula flavae are probably required for metabolism of the extracellular matrices of the vocal fold mucosa, replacing damaged fibers in order to maintain the integrity and elasticity of the vocal fold tissues. Age-related changes in the macula flava influence the fibrous components of the vocal folds and are partially responsible for the differences in the acoustics of the adult and aged voice.
   It is not uncommon for adolescents to have certain linguistic variation in their speech. Adolescence is a transitional period when children become adults and move away from their family identity to express themselves as individuals. During this period, age-segregated networks form, giving rise to age-graded variation. Adolescents tend to lead with an increased use of vernacular and linguistic variables to differentiate themselves from the adult population.
   There is a steady increase in the elastin content of the lamina propria as humans age (elastin is a yellow scleroprotein, the essential constituent of the elastic connective tissue) resulting in a decrease in the ability of the lamina propria to expand caused by cross-branching of the elastin fibers. Among other things, this leads to the mature voice being better suited to the rigors of opera.
  