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Sample Final Exam

  • 以獨立的紙張回答下列10個問題。
    Answer each of the 10 questions on a separate sheet of paper.

  • 每個問題不使用超過一頁紙張。
    Do not use more than one page per question.

  • 以簡短的段落回答每個問題。
    Answer each question by a short paragraph.

  • 若可幫助表達,可使用表格或手繪草圖。
    You are encouraged to use tables and hand-drawn sketches if it helps clarity.

  • 每個問題的加權計分等同。
    All questions will be weighted equally for grading.

1.Tonotopic mappings are found throughout the auditory pathway.

a) State a specific nucleus or region that is tonotopically mapped. Be more specific than “brainstem” or “cortex”.

b) For the region you chose in part a, describe the orientation of the tonotopic axis (e.g., medial to lateral; high frequency to low frequency).

c) 陳述在a部分你所選擇的區域裡,一個確定是沿著tonotopic軸直角方向投映的刺激特性。
c) For the region you chose in part a, state one stimulus property that has been claimed to be mapped along a direction orthogonal to the tonotopic axis.

2. What is meant by the terms resolved and unresolved harmonics? Describe their respective roles in pitch perception. How would you determine physiologically if a given set of harmonics is resolved?

3.心理物理測量在依據以下情況實行:(1)頻率1000赫茲、反應時間20毫秒的探測音其聲音位準高於靜音臨界15分貝(如15分貝的感覺層次),(2)將反應時間300毫秒的遮蔽音,其位準調整到可聽聞試驗中75%的探測音 (如探測音仍然在其「遮蔽門檻」內),遮蔽音和探測音兩者斷斷續續地跳動,以避免頻譜散射。

3. Several psychophysical tests were done using (1) a 1000 Hz, 20 ms probe tone at a sound level 15 dB above the subject's threshold in quiet (i.e. 15 dB SL), and (2) a 300-ms masker tone whose level was adjusted until the probe could be heard on 75% of the trials (i.e. the probe was at its "masked threshold"). Both masker and probe were ramped on and off to avoid spectral splatter.

初始,遮蔽者頻率被設定在1000赫茲,則遮蔽門檻可在兩種情況下被測量得知:第一種情況探測音出現在遮蔽者即將產生之前,其所得之遮蔽門檻為LB1000。 另一情況當探測音出現在遮蔽者產生之後,可得遮蔽門檻為LA1000。兩種情況下的遮蔽門檻皆祇在幾分貝而已 如 LA1000 ≈LB1000

Initially, the masker frequency was set to 1000 Hz. Masked thresholds were measured in two conditions. In one condition, the probe occurred just before the end of the masker. The resulting threshold masker level was LB1000. In the other condition, the probe occurred just after the end of the masker, giving a threshold masker level LA1000. The thresholds were found to be within a few dB of each other in both conditions, i.e. LA1000 ≈ LB1000.

然後,將遮蔽頻率增加到1060赫茲,當所有變數維持相同的狀態下重新測量其遮蔽門檻。當探測音出現在遮蔽者產生之前,其遮蔽門檻為 LB1060;當探測音出現在遮蔽者產生之後,其遮蔽門檻為 LA1060

he masker frequency was then increased to 1060 Hz, and the two threshold measurements repeated with all other parameters remaining the same. The resulting threshold masker levels were LB1060 and LA1060 for the probe presented before and after the end of the masker, respectively.

Answer the following two questions:

a) LA1060LA1000,何者較大,解釋其理由。
a) Which is greater, LA1060 or LA1000? Explain.

b) Which is greater, LB1060 or LA1060? Explain.


4. Coincidence detection is a general neural mechanism which plays a role in binaural hearing and, possibly, in intensity coding and pitch extraction as well. Below are listed some cellular characteristics of coincidence detector neurons. For each of these, state whether (1) it is essential for coincidence detection, (2) it is not a necessary feature, but may help coincidence detection in some cases, (3) it is largely irrelevant. Give a brief explanation for each answer.

a) 興奮性的輸入是低於閥值
a) Their excitatory inputs are subthreshold.

b) 抑制性的輸入被限制在體細胞與樹突近側
b) Their inhibitory inputs are restricted to the soma and proximal parts of dendrites.

c) 從延遲線輸入
c) Their inputs form delay lines.

d) 擁有低閥值、外流的鉀離子傳導
d) They possess low-threshold, outward-rectifying potassium conductances.

e) 兩極形式
e) They have bipolar shapes.

f) 膜時間係數很短
f) They have short membrane time constants.

5. 聽覺系統中耳蝸神經核被認為是平行功能性途徑的起源。試寫出一小段證實此觀點的生理學證據。

5. It is often stated that the cochlear nucleus is the origin of parallel functional pathways in the auditory system. Write a short paragraph that provides physiological evidence for this view.

6. Siebert (1968)模型可預測強度辨識,Weber’s定律主要藉由位於反應刺激的tonotopic興奮模式邊緣之未飽和聽覺神經纖維所提供的資訊來分析純音。提供反駁這些模型的心理物理學證據。並回答是否興奮性的延展在強度編碼或響度感知中是否扮演其他的角色?
(譯註:W.M. Siebert.,〈周邊聽覺系統的刺激轉換〉,《識別型態》,由P.A. Kolwers 與 M. Eden編輯,劍橋,麻州,麻省理工學院出版社,1968,104-133)。

6. The Siebert (1968) model for intensity discrimination predicts Weber’s law for pure tones by relying on information from unsaturated auditory nerve fibers located on the edges of the tonotopic excitation pattern produced the stimulus. Give psychophysical evidence against this model. Does spread of excitation play another role in intensity coding or loudness perception?

7. 聽覺反應主要由兩種聽覺神經纖維所測量,將其分別以特性頻率的音調刺激 (高於聽閥10分貝)。將頻率為40赫茲,音壓位準100分貝的低頻「乖離」音調加諸於特性頻率音調,並在頻率40赫茲的區域下計算其週期統計圖。結果發現其中一種聽覺神經纖維在頻率40赫茲的單相情形下顯示出抑制作用;另一種聽覺纖維則顯示出近乎180度雙相背離的抑制作用。解釋造成此抑制現象的原因,並針對兩種聽覺纖維的差異提出合理的假設。

7. Responses were measured from two auditory-nerve fibers, each stimulated with a tone at its characteristic frequency (CF), 10 dB above threshold. A low-frequency, "bias" tone of 40 Hz, 100 dB SPL was added to the CF tone and period histograms were calculated at the period of the 40 Hz tone. One fiber shows suppression during a single phase of the 40 Hz tone, while the other fiber shows suppression at two phases approximately 180 degrees part. Explain what causes the suppression and give one plausible hypothesis for why there is a difference between the two fibers.

8. 描述兩項聽覺系統表現純音頻率的週邊神經編碼模式。其支持和反對的心理物理學證據分別為何?

8. Describe two peripheral neural codes that could be used by the auditory system to represent the frequency of pure tones. What psychophysical evidence is there for or against these coding mechanisms?

9. 陳述兩個用以假設說明聽覺神經皮質投映之可塑性的神經機制。

9. State two neural mechanisms that have been hypothesized to account for the plasticity of auditory cortex mappings.

10. 描述兩個可加強雙耳在雜訊中理解語音的因子。解釋它們如何作用以及在哪一段頻率區域其影響最為顯著。

10. Describe two factors that contribute to binaural advantages in speech intelligibility in noise. Explain how they contribute and in which frequency region they are the most effective.

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