puter-science/aqa/questions","basePath":"/gcse/computer-science/aqa/representing-sound/questions","formulaUrl":null,"initialIndex":3,"initialQuestionWindow":[{"id":"03757f99-c78e-4c15-95d2-7d246d64b845","revisionId":"66bec2d7-37ab-42d6-b2f7-a59f3248a6b9","questionNumber":null,"questionType":"LA","specification":"An oceanographer uses an underwater hydrophone to capture a whale's low-frequency vocalisation. The hydrophone registers this sound as a continuous electrical signal (voltage representing acoustic pressure waves), as shown in the analogue-to-digital diagram below:\n\n![Analogue-to-Digital Conversion](https://assets.mathsgenie.co.uk/aqa-qb/9cb01c12-f9db-4e23-a844-4ac9af21cd99.png)","difficulty":5,"difficultyBand":"medium","totalMarks":3,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"865e569b-70ed-4fd9-a127-bdbcfee00f92","label":null,"content":"Describe the sequence of steps required to convert this continuous analogue voltage signal into a digital format suitable for storage on a marine data logger.","markscheme":"- Explains that the continuous analogue voltage signal is measured (sampled) at fixed, regular time intervals (at a specific sampling rate) M1\n- Explains that the amplitude or voltage level of each individual sample is measured and mapped/rounded to the nearest predefined discrete value (quantisation) A1\n- Explains that these discrete numerical values are converted into a sequence of binary numbers (digital representation) and saved in a sequential order to form the digital audio file A1","marks":3,"order":0,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"0c929a54-fb8c-41fe-9a48-18276c01c0fa","revisionId":"ed9ee478-d2ef-48d2-84ca-4d0ca02aab46","questionNumber":null,"questionType":"LA","specification":"An acoustic monitoring station is deployed in a nature reserve to record the ultrasonic echolocation calls of bats. The digital recorder captures audio at a sampling rate of 192,000 Hz and a sample resolution of 24 bits.","difficulty":4,"difficultyBand":"medium","totalMarks":4,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"44cc693a-18a3-457c-b649-05e5b6970ee5","label":null,"content":"Calculate the minimum file size, in bytes, of a continuous recording lasting 2.5 seconds.\n\nYou should show your working.","markscheme":"- Identifies the need to use the formula $\\text{File size} = \\text{Sampling rate} \\times \\text{Sample resolution} \\times \\text{Duration}$ or writes down the product: $192,000 \\times 24 \\times 2.5$ M1\n- Calculates the total size in bits as $11,520,000$ bits OR converts the 24-bit resolution to $3$ bytes ($24 \\div 8$) A1\n- Shows division of the total bits by 8 to convert to bytes: $\\frac{11,520,000}{8}$ OR calculates file size directly as $192,000 \\times 3 \\times 2.5$ M1\n- Obtains the correct final answer of $1,440,000$ (or $1,440,000\\text{ bytes}$) A1","marks":4,"order":0,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"10a9b4e6-f4c7-4c32-99aa-5c663c2c5057","revisionId":"3e9eb450-9f72-4d31-b712-26dafd1c3911","questionNumber":null,"questionType":"LA","specification":"A software developer is recording a voice clip for a mobile application. The audio is recorded with a sampling rate of 3,000 Hz and a sample resolution of 16 bits.","difficulty":3,"difficultyBand":"medium","totalMarks":4,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"55395213-9720-4e7d-ba71-72a4c2695e5e","label":null,"content":"Calculate the minimum file size of an 8-second audio recording. Give your answer in **bytes**.\n\nYou should show your working.","markscheme":"- Shows substitution of correct values into the formula: $3,000 \\times 16 \\times 8$ M1\n- Obtains a correct intermediate calculation of $384,000$ bits OR converts $16$ bits to $2$ bytes M1\n- Divides by $8$ to convert bits to bytes (or demon

Representing sound

Question 3

Representing sound Questions

Representing sound

Question 3

Representing sound Questions