八年级物理探究声音是怎样传播的3

7、回声是指在声音传播过程中 （ ）在传入耳朵的声音，回声 到达人耳比原声晚（ ）人耳 能把原声和回声区分开。 8、在峡谷中呼喊后会听到回声， 假如从呼喊到听到回声用了3s， 则反射声音的高山离你（ ）m。
9、利用回声可以测定海底 深度，需要先知道（ ）， 需要测出（ ），然后利用 （ ）进行计算。
探究声音是怎样传播的
山东省无棣县埕口中学 蔡建宏
振动物体通过什么把振 动传给我们的耳朵引起 听觉的呢？
三、声音靠介质传播 介质： 声音能够靠任何气体、液 体、固体物质作媒介传播 出去，这些作为传播媒介 的物质称为介质
V> V> V
固 液
气
1、一切正在发声的物 体都在（ ），（ ）停止， 发声也停止，人说话唱歌靠的是 （ ）的振动。 2、声音的传播靠（ ），一切 （ ）（ ）（ ）物质作媒介都 能传播声音， 通常人耳能听到声音是因为声音可 通过（ ）传入耳引起耳膜的 （ ）。
/ 上海外围招聘
-day where there are so many little foreigners not born in this country or whose parents haven’t been long here. She” —dreamily soliloquizing, with a glance at that lavender-smocked figure—“said that, last year, she and the other members of the Akiyuhapi Camp Fire in that Pennsylvania n milling town, where she became a Camp Fire Girl, did so much voluntary work upon the public playground, largely among the little immigrants, teaching them American songs, American games, telling them stories, settling their squabbles. Well! I guess I’m not going to bother her with questions about her ‘Mo rning-Glory’ name just now. Over there where she’s standing”—flashing another glance at the gray auto, with two girls in it and one leaning against its silver do or-knob—“I’d have to bray like a jackass to be heard above the music of that absurd piano, perched upon a low cart. Goody!” with a sudden, excited move ment of her vivid shoulders. “I shouldn’t like to be that perched-up pianist. Just suppose the playground horse should take it into his head to pop —to dance—to chase the weasel, too?”Was it any suddenly restless movement on the part of that four-footed servant of the city which drew the strolling piano upon a low cart from playground to playground to thresh out music for the children’s dances—was it that which flashed the thought backward over his flicking tail, over the head of the pounding pianist seated upon a light cane chair before the lashed piano, flashed it into Sally’s brain? That, or the elfin dance of su nbeams upon his stamping hoofs which, together with the popping dance-cries of the children and the louder popping of the musical instrument behind him —deliriously out of tune, too—must surely infect the staidest horse?Sally did not know which launched the apprehension, the tickling sunbeams or the restless ho ofs and head. But she was used to horses. She found herself mechanically straightening up, controlling the giddy dance-spirit in her own soles, moving nearer —nearer—to the low cart as if she could not help it.A brilliant orange streak in the sunlight she, flecked oriole-like with black, from the velvet ribbon that lent tone to that saucy little Tam, to the black needlework stars upon the heaving girlish breast.Then all at once this human flame -bird weaving its way in and out between sets of dancing children was halted by a musical crash, brought up short on tiptoe by a screaming commotion through which rang a nightmare of treble c hords wildly sustained by the pianist’s right hand blundering among the shrieking keys of the elevated piano, while her left arm waved on high, imploring help, the whole seeming a premature, mad finale to the popping music, to which every voice upon the playground, animate and inanimate, lent a cry —discordantly at that!The effect was so feverishly funny that Sally, who had the oriole’s gay spirit within her orange -smocked breast, vented a shriek as loud as any, to swell the confusion, automatically clapping her fingers to her ears.The voices of some fourscore children had popped explosively from song and shout to scare -note and shriek, a conglomerate shriek, strengthened by every foreign accent under the sun (any cry ever hurled from the crumbling Tower of Babel was nothing to it!), a shriek that hung, sustained, in air together with the rasping, squelching notes of that unfinished musical measure which seemed to tatter the a ir itself.“Ouch! My s-soul!” murmured Sally under her breath. “The horse! It’s the—horse. He is bolting, with the piano lashed to the cart behind him. And the—poor—pianist!”It needed no more. She saw the girl-musician’s left arm waving, imploring, saw her rock upon the light cane chair before the instrument th at was not lashed to the rocking cart; she heard the horse’s mutinous snort, heard it strangely echoed in dumb fashion by a pair of parted childish li ps near her; crowning all, she caught the terrified shriek of a small boy who clutched at his raven-black hair and what English he could muster as he started toward a sand-pile ahead, yelling, “Mine babee—mine babee! Horse he go kill her; she —she go all—deaded!”And like the flame from the cloud leaped the answering fire in Sesooā—little Camp Fire Girl!“The driver—the boy driver—he ought to be shot; he’s umpiring a baseball game,” was the first distinct thought that le aped to her mind as, like an oriole on the wing, she sped across the sunlit grass in the wake of the still rocking cart, the fiendishly howling piano, the screaming, swaying pianist. The second lightning conviction was: “It’s up -hill and the horse can’t really run very fast with that absurd piano behind him! He’s dancing all over the place, rather than wildly running, now!... Rolie showed me —has told me so often—how to stop a runaway!”Rolie was her Boy Scout brother and that gallant fourteenyear-old Scout seemed to run neck and neck with her in this crisis, whispering heart into her, advising her movements.The firefl y in her eyes, soaring, golden, above consternation, has lit now upon the horse’s quivering haunch—on his black mane.“After all, he’s only a horse; I’ve not alo ne ridden one, but, as a Camp Fire Girl, have saddled and bridled and fed an’ currycombed it, too, every day for the past month!” whizzed thought, dar ting ahead of her as with another springy step or two her right hand has seized the cart’s shaft to hold on and prevent herself from falling in the supreme eff ort she is about to make.Her left hand, attached to a strong little wrist for a girl not yet sixteen, has snatched at the dragging reins, holding them short, i s trying to pull the horse’s head down, turn it toward her!Only a horse! And a brother-horse was such a friend of hers! The firefly bore that thought upon its wings as it wheeled above doubt, resistance, wrenching strain that was tugging her soft young arms from their sockets —her feet from the solid earth.Only a horse! But a maddened horse, distracted by the shrieking ivories behind him!Her girl’s strength against his!Yet his rebel -crest was lowering. His lifted forelegs were uncurling, the waving hoofs that cared not what they smashed returning sanely to the sod.And