omputer-science/aqa/questions","basePath":"/gcse/computer-science/aqa/representing-sound/questions","formulaUrl":null,"initialIndex":33,"initialQuestionWindow":[{"id":"cc75d207-3e1a-4878-97e4-28a9f8bfb7c0","revisionId":"0dd68978-0138-41f4-be04-734eb0c9f5c0","questionNumber":null,"questionType":"LA","specification":"A sampling rate of 40,000 Hz and a sample resolution of 16 bits is used to make a digital recording of a sound that lasts 150 seconds.","difficulty":4,"difficultyBand":"medium","totalMarks":3,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"d533cbf1-b75f-4714-9dc0-5d314a09a3f6","label":null,"content":"What is the minimum file size of the recording in megabytes (MB)?\n\nAssume 1 kilobyte (kB) = 1,000 bytes and 1 megabyte (MB) = 1,000,000 bytes.\n\nYou should show your working.","markscheme":"- Calculates the total number of bits: $40,000 \\times 16 \\times 150 = 96,000,000$ M1\n- Converts bits to bytes by dividing by $8$ to obtain $12,000,000$ bytes (or converts $16$ bits to $2$ bytes early: $40,000 \\times 2 \\times 150 = 12,000,000$) M1\n- Converts bytes to megabytes by dividing by $1,000,000$ to find the final minimum file size of $12\\text{ MB}$ A1","marks":3,"order":0,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"ce9396bf-4cf8-42ae-9bbd-a7656c3bb214","revisionId":"3fae0d80-9f90-474a-a67f-674353f67a5c","questionNumber":null,"questionType":"LA","specification":"","difficulty":4,"difficultyBand":"medium","totalMarks":3,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"c6761a1d-4c3a-41d0-a1aa-8c362b8517b4","label":null,"content":"An autonomous marine research drone uses an underwater hydrophone to record the low-frequency acoustic vocalizations (continuous analogue sound waves) of blue whales.\n\n![Analogue-to-Digital Conversion](https://assets.mathsgenie.co.uk/aqa-qb/d377f50d-a350-49f8-b2b2-799f946bb042.png)\n\nDescribe the physical and mathematical process of Analogue-to-Digital Conversion (ADC) illustrated above, explaining how the continuous analogue wave from the hydrophone is transformed into a digital format suitable for storage on the drone's solid-state drive.","markscheme":"- State that the continuous analogue acoustic wave is measured or sampled at regular, periodic time intervals (the sampling rate) M1\n- Explain that the amplitude or voltage of the wave at each sample point is measured and mapped/rounded to the nearest discrete quantised integer value A1\n- Explain that these discrete numerical values are converted into binary numbers and saved sequentially as a stream of binary data on the storage device A1","marks":3,"order":0,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"edb26b8b-fc22-4206-bb66-977a7d7596ec","revisionId":"0bfeabec-cf0f-4c87-a01f-414de1a29bc9","questionNumber":null,"questionType":"MC","specification":"An audio engineer is remastering a mono recording. They decide to double the sampling rate from $22\\text{ kHz}$ to $44\\text{ kHz}$ but decrease the sample resolution (bit depth) from $24\\text{ bits}$ to $16\\text{ bits}$.\n\nWhich of the following correctly describes the combined effect of these changes on the file size of the recording and the number of unique amplitude levels that can be represented?","difficulty":7,"difficultyBand":"medium","totalMarks":1,"sourceTitle":null,"calculatorUse":null,"parts":[],"options":[{"id":"5783e57b-a47e-4b9e-a0c2-6dd3ec740304","content":"The file size increases by $33.3\\%$, while the number of unique amplitude levels is reduced by a factor of $256$.","correct":true,"markscheme":"Correct. The file size increases by a factor of $2 \\times \\frac{2}{3} = \\frac{4}{3}$ (a $33.3\\%$ increase), and the number of amplitude levels changes from $2^{24}$ to $2^{16}$ (reduced by a factor of $2^8 = 256$).","order":0},{"id":"5f69353e-030a-4d00-9d50-9ba69f01acbf","content":"The file size increases by

Representing sound

Question 13

Representing sound Questions

Representing sound

Question 13

Representing sound Questions